Answer:
1. by not avoiding air bubbles from being trapped in the burette or pipette when filling them
2. not cross-checking the burette if it's slanted or vertically clamped
3. forgetting to rinse the pipette or burette with the solution to be used
4. not considering to take readings from the bottom of the meniscus with the eye level
5. finally, adding more than three drops of indicators to the pipetted solution
Explanation:
1. because the air bubbles will be mistakenly considered as part of the amount of the solution taken instead of that actually used up, and a higher titre value would be obtained
2. because if it's slanted, the acid level will be titled to one side and wrong reading will be recorded
3. rinsing to avoid diluting the acid or base with water that wets the burette or pipette
4. to avoid error of parallax and helps you to obtain accurate readings
5. excess burette solution than would normally have been consumed would be used up to change the colour of the indicator
Titration has been defined as the neutralization reaction for the acid and base, resulting in the formation of salt and water. It has been used for the determination of strength of acid and base.
The general source of error in titration has been;
The measurement of volume in burette by at the lower meniscus. It has been corrected with the application of measurement at eye level.The air bubble in the burette results in the incorrect measurement of the volume of burette. It can be corrected by tapping the burette or by slowing adding the solution to remove the bubble.The absence of rinsing the burette before use has been resulted in the water droplets that has been results in the incorrect measurement and dilution of the solution. The correction has been made by the use of dried burette.The titration error has generally being manual error, and can be easily corrected.
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Now molecules: ____ molecules of H2 + ____ molecules of O2 → ____molecules of H2O
Answer:
4 H2 + 1 O2 = 2 H2O
A chemist dissolves 398. Mg of pure hydrochloric acid in enough water to make up 210. ML of solution. Calculate the pH of the solution. Round your answer to 3 significant decimal places.
Answer:
THE pH OF THE SOLUTION IS 1.28
Explanation:
Step 1: Calculate the mass concentration of HCl
398 mg in 210 mL
1 L = 10^3 mL
1 g = 10^3 mg
398 *10^-3 g in 210 *10^-3 L
398 *10^-3 in 0.210 L
mass concentration = (0.398 * 1/ 0.210) g/dm3
= 1.895 g/dm3
Step 2: calculate the molar concentration
Molar mass of HCl = ( 1 + 35.5) = 36.5 g/mol
Molar concentration = mass concentration / RMM
Molar conc. = 1.895 / 36.5
Molar conc. = 0.0519 mol/dm3
So therefore, the molar concentartion of the solution is equal to the concentration of HCl.
In other words, [HCl] = 0.0519 mol/dm3
This shows that at 1 L of this solution contains 0.0519 moles of HCl
Step 3: write the dissiociation equation of HCl in water
HCl(aq) + H2O(l) --------> H30^+ (aq) + Cl- (aq)
Since HCl is a strong acid, it will dissociate completely in water forming the above products.
So we can say that:
[H3O+] = [HCl] = 0.0519 moles/ dm3
Step 4: calculate the pH
pH = -log[H3O+]
pH = -log (0.0519)
pH = 1.28(3 significant decimal place)
The pH of the solution is 1.28
what is microbial oxidation?
Answer:
Bacteria biooxidation is an oxidation process caused by microbes where the valuable metal remains (but becomes enriched) in the solid phase. In this process, the metal remains in the solid phase and the liquid can be discarded.Hope it helps you!
Answer Microbial oxidation of sulfur is the oxidation of sulfur by microorganisms to produce energy. The oxidation of inorganic compounds is the strategy primarily used by chemolithotrophic microorganisms to obtain energy in order to build their structural components, survive, grow and reproduce.
Explanation:
Which of the following elements will sulfur most readily react with in order to help it fill its outer shell with 8 electrons?
arsenic (As)
astatine (At)
argon (Ar)
magnesium (Mg)
Answer:
Magnesium
Explanation:
Using the KLMN styled electronic configuration, the electronic configuration of sulphur with atomic number 16 is 2, 8,6
What this means is that it needs extra 2 electrons to fill into its M shell to attain the octet configuration.
Now let’s look at Magnesium, with atomic number 12, the electronic configuration it has is 2,8,2.
This means it has 2 extra electrons to give away so as to attain its own stability.
The sulphur atom will gladly accept the two electrons which the magnesium atom wants to give away. This makes it the perfect element to be reacted with sulphur to make it attain its octet configuration
What happens when a piece of Mg ribbon is burnt? Name the
new substance formed. Write a balanced chemical equation.
Answer:
When a Magnesium Ribbon is burnt, a powdery substance called magnesium oxide is formed.
Explanation:
There has obviously been a chemical change because several chemical properties of the magnesium have been modified: the color, the texture and the mass.
The increase in mass is due to the fact that oxygen from the air has combined with the magnesium to make magnesium oxide, MgO.
The chemical equation, Mg + O2 MgO shows this reaction but it needs to be balanced to make 2Mg + O2 2MgO.
Using stoichiometry, we can convert this eqation into an equation with moles:
2 mol Mg + 1 mol O2 2 mol MgO.
Next, we convert to grams using atomic masses obtained from the periodic table:
48g Mg + 32g O2 80g MgO
Lastly, we determine the same thing in the proportions we used. In other words, we used only 0.15g of Mg (not 48g) so everything needs to be divided by 320. So 80 / 320 = 0.25 g. If we burn 0.15 g of Mg, we obtain 0.25 g of MgO.
Hope this helps!!!
This is my first answer.
what is the pOH of 2.5 M NaOH
Answer:
-0.398
Explanation:
pOH is a measure of hydroxide ion (OH-) concentration in a solution. A basic solution If a solution has pOH less than 7 then it is a basic solution and if pOH is greater than 7 then it is an acidic solution. Neutral solutions have pOH equal to 7.
[tex]pOH=-\log \left [ OH^- \right ][/tex]
To find pOH of 2.5 M NaOH, solve [tex]pOH=-\log \left [ 2.5 \right ][/tex] = -0.398
Why are some areas rich in certain resources, while other areas don’t seem to have any natural resources
Answer:
The geographical occurrence or spatial distribution of earthly resources made them abundant at some place and lacks at other.
Explanation:
Low latitudes regions receive more energy and plenty of rainfall from the sun, while higher latitudes obtain less energy from the sun and little rainfall. Metallic minerals are easily available in regions with strong tectonic activity, and fossil fuels are found in sedimentary rocks. The plains deliver flat landscapes and rich soil which is ideal for growing crops, on the other hand, steep hills and dry areas are more difficult for the activity. Therefore climate and geography play a vital role in the uneven distribution of natural resources across the globe.
name the scientist who studied the movement of pollen grains suspended in water through a microscope what is the phenomenon known as
Answer:
the scientist who studied the movement of pollen grains grains suspended in water through a microscope is Robert Hooke
if a plant needs to make 12.6 g of glucose(c6h1206), how many grams of water are required?
Answer: 7.6 g of water are required to make 12.6 g of glucose
Explanation:
Moles is calculated by using the formula:
[tex]Moles=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]
[tex]{\text {moles of glucose}}=\frac{12.6g}{180g/mol}=0.07moles[/tex]
The balanced chemical equation is:
[tex]6CO_2+6H_2O\rightarrow C_6H_{12}O_6+6O_2[/tex]
According to stoichiometry:
1 mole of glucose is produced by = 6 moles of water
Thus 0.07 moles of glucose is produced by =[tex]\frac{6}{1}\times 0.07=0.42[/tex] moles of water
Mass of water required =[tex]moles\times {\text {Molar mass}}=0.42mol\times 18g/mol=7.6g[/tex]
Thus 7.6 g of water are required to make 12.6 g of glucose
Given the unbalanced equation below, how many moles
of Li would be needed to produce 6 moles of LiCl?
Li + Cl2 → Lici
Answer: 6 mol Li
Explanation:
The first step is to balance the equation.
2Li+Cl₂⇒2LiCl
We would need our conversions to find the amount of moles of Li needed to produces 6 mol LiCl.
[tex]6molLiCl*\frac{2molLi}{2molLiCl} =6molLi[/tex]
How many moles of CO2 is needed to fill an 80.0 L tank to a pressure of 150.0 atm at 27.0°C?
Answer:
487 moles of CO2 is needed
Explanation:
What we need to use here is the ideal gas equation.
Mathematically;
PV = nRT
Since we are calculating the number of moles, we can rewrite the equation to be;
n = PV/RT
from the question, we identify the following;
P is the pressure at 150 atm
V is the volume at 80L
T is the temperature which is 27+273 = 300K
R is the molar gas constant which is 0.0821 L atm K^-1 mol^-1
Substituting these values, we have;
n = (150 * 80)/(0.0821 * 300) = 487.2 which is approximately 487 moles
Given 700 ml of oxygen at 7 ºC and 106.6 kPa pressure, what volume does it take at 27ºC and 66.6 kPa pressure
Answer:
1.20 L = 1200 mL
Explanation:
P1V1/T1 = P2V2/T2
V2 = P1*V1*T2/(T1*P2)
V1 = 700ml =0.700 L
P1 = 106.6 kPa
T1 = 7+273.15 = 280.15 K
T2 = 27 + 273.15 = 300.15 K
P2 = 66.6 kPa
V2 = 106.6*0.700*300.15/(280.15*66.6)= 1.20 L=1200 mL
Click on the diagram to choose which atom is more reactive.
Answer:
Second graph is more reactive.
Explanation:
I just did the lesson myself, chose the first graph, and obviously got it wrong.
Therefore I can tell you with 100% certainty that the correct answer is graph #2 in this case. Hope this helps.
A compound, X contains 92.31 % C and 7.69 % H.
RMM of X is 78. Determine the molecular formula.
Answer:
C6H6
Explanation:
Just use the table method to find the ratio of C to H and then compare the RMM with that of the empirical formula.
Answer:
C6H6
Explanation:
We divide each percentage by the relative atomic mass of the element:
Carbon: 92.31 / 12.011 = 7.68
Hydrogen: 7.69 / 1.008 = 7.63
So the ratio of carbon to hydrogen is 1:1.
Empirical formula is CH - which has a MM of 13.019
The RMM is 78 so the molecular formula = 78/13.019 = 6 * CH
So it is C6H6 (Benzene).
A chemist dilutes 185 of the 3.0 M solution with water until a new volume of 750 is obtained. Calculate the new concentration
Answer:
0.74M
Explanation:
Step 1 :
Data obtained from the question.
Initial concentration (C1) = 3M
Initial volume (V2) = 185mL
Final volume (V2) = 750mL
Final concentration (C2) =..?
Step 2:
Determination of the new concentration of the solution.
The new concentration of the solution can be obtained by using the dilution formula as shown below:
C1V1 = C2V2
3 x 185 = C2 x 750
Divide both side by 750
C2 = 3 x 185 / 750
C2 = 0.74M
Therefore, the new concentration of the solution is 0.74M
Non-native species are typically introduced into an area because they serve a purpose. Why was kudzu introduced into the United States? Check all that apply.
Answer:
Explanation:
The Kudzu is a plant that was introduced to the United States from Japan in the year 1876. In the United States it was introduced as an ornamental plant but with a reason which was to prevent soil erosion. Kudzu was disseminated as being high-protein content used to steer feed as well as a spreading plant to counteract soil erosion.
Answer:
Kudzu was introduced as an ornamental plant.
+
Kudzu was introduced as a way of preventing soil erosion.
So, A and D!
The number of electrons can accommodate in K shell is 8. True or False
Answer:
true
no explanation
Which element below contains 10 protons?
the le answer to dis problem is neon. it has 10 protons
Consider the unit cell of aluminum with aluminum ion on every corner and every face-centered site of the cube.
Question
1. Using the value of ionic radius of aluminum ion r=0.143 nm, the length of each edge of the unit cell can be calculated as what nm?
2.Using atomic weight value of aluminum 27.0, the density of aluminum can be calculated as what g/cm^3
Answer:
1) 0.4045nm
2) 0.0027096117g/cm³
Explanation:
1) Using the value of ionic radius of aluminum ion r=0.143 nm, the length of each edge of the unit cell can be calculated as what nm?
In the question above, using a face centered cubic structure, we have:
For a face centered site of the cube,
The diagonal = 4r
Where r =Atomic or ionic radius of Aluminum
Let the edge length of the cube be represented by X
Therefore, we have based on Pythagoras theorem,
X² + X² = (4r)²
2X² = 16r²
Divide both sides by 2
X² = 8r²
Find the square root of both sides
X = √8 × r
Since r = 0.143nm
The length of each edge of the unit cell can be calculated as
X = √8 × 0.143nm
X = 0.4044650788nm
Approximately = 0.4045nm
2) Using atomic weight value of aluminum 27.0, the density of aluminum can be calculated as what g/cm^3
Density of an object = Mass of the Object / Volume of the Object.
The object in this question = Cube
Step 1
Volume of a cube = (Length of the cube)³
In the question above, side length of the cube = 0.4045nm
When would convert 0.4045nm to centimeters
= 1 nm = 1 × 10^-7 cm
0.4045nm =
Cross multiply
= 4.045 × 10^-7 cm
Volume of the Aluminum cube =(4.045 × 10^-7cm)³
= 6.618439112 ×10^-20cm³
Step 2
The atomic weight value of aluminum is given as 27.0 in the question
A face centered cubic structure has 4 atoms per unit cell.
1 Atomic mass or weight value = 1.6605 × 10^-24 grams
Hence, the mass of Aluminum is calculated as:
(4 atoms /1 cell )× 1 unit × (27/ 1 atom of Aluminium) × (1.6605 × 10^-24g/ 1 Atomic mass value)
= 1.79334 ×10^-22g
Density = Mass/Volume
= 1.79334 ×10^ -22g /6.618439112 ×10^-20cm³
= 0.0027096117g/cm³
Calculate the molarity of a solution that has 2.02 mol KNO3 in a 250.0
mL solution.
Explanation:
Molarity = M = mol/1 liter
in sol 250 mL there are KNO3 2.02 mol
in sol 1000 mL there are KNO3 = 2.02/250 × 1000
= 8.08 mol/liter
Which structural formula represents a member of the alkene series?
Answer:
C4H8. butene
The stock solution of hydrochloric acid is 12.0M HCI. If the teacher starts with 130 ml of this concentrated acid, what volume of 3.0M HCI can be prepared?
Answer:
520mL
Explanation:
Data obtained from the question include:
Molarity of stock solution (M1) = 12M
Volume of stock solution (V1) = 130mL
Molarity of diluted solution (M2) = 3M
Volume of diluted (V2) =..?
The volume of the diluted solution can be obtained as follow:
M1V1 = M2V2
12 x 130 = 3 x V2
Divide both side by 3
V2 = 12 x 130 / 3
V2 = 520mL.
Therefore, 520mL of the diluted solution can be prepared.
Will give BRAINLIEST: Is a new theory of light and matter needed to explain what happens at very high energies and temperatures?
Explanation:
All of that visible trail of radiation, especially in the form of gamma rays—the extremely energetic cousins of ordinary light. Astronomers have known for three decades that brilliant flashes of these rays, called gamma-ray bursts, arrive daily from random directions in the sky. Recently astronomers have pinned down the location of the bursts and tentatively identified them as massive supernova explosions and neutron stars colliding both with themselves and black holes. But even now nobody knows much about what goes on when so much energy is flying around. Matter grows so hot that it interacts with radiation in unfamiliar ways, and photons of radiation can crash into each other and create new matter. The distinction between matter and energy grows blurry. Throw in the added factor of magnetism, and physicists can make only rough guesses about what happens in these hellish settings. Perhaps current theories simply aren’t adequate to explain them.
Which statement correctly describes metallic bonds?
A.
They form when certain atoms lose electrons and other atoms gain electrons.
B.
They involve an attraction between anions and cations.
C.
They always involve both a metal and a nonmetal.
D.
They can only form between atoms of the same element.
E.
They form because electrons can move freely between atoms.
Answer: D
Explanation:
the atom of the metal loses one electron which becomes delocalised and is attragted by the positive nucleus leading to formation of metallic bond.
E. They form because electrons can move freely between atoms
Top guy is incorrect↑
#Platofam
8. What are two physical changes that cooling a hot substance may result in?
Answer:
Explanation:
Two possible changes are
a phase change. If water is presented in the form of steam, it may change into liquid, or eventually into a solid. While in a phase change, the temperature might change.a temperature change. Water at 65o what cooled can go down to 5o. There is no phase change, but there is a temperature change.This right guys? plz help
Which of the following are considered pure substances? element compound homogeneous mixture heterogeneous mixture
Answer:
element and compound.
Explanation:
reason
an element is a pure substance that cannot be broken down into simpler substances by any ordinary physical or chemical process.
and compound is a pure substance that consists of two or more elements held together in fixed proportions by natural forces called chemical bonds.
homogeneos and heterogenous mixtures are considered impure substances because they dont have a definite composition.
In chemistry, pure substances have been defined by matter that has characteristic properties. An element and compound are pure substances. Thus, options 1, and 2 are correct.
What are pure substances?Pure substances have been the matter that is characterized by the presence of a fixed chemical composition that cannot be physically separated by the processes like filtration, evaporation, etc.
Elements and compounds are pure substances as elements are not broken physically or chemically to form simple -small substances like zinc. Furthermore, compounds are formed by the combination of pure substances like water.
Homogeneous mixtures and heterogeneous mixtures are not pure substances as they lack fixed ratios and proportions that cannot be said to have definite composition.
Therefore, options 1 and 2. are elements and compounds are pure substances.
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ASSERTION AND REASON DIRECTION : In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as: (a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A). (b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A). (c) Assertion (A) is true but reason (R) is false. (d) Assertion (A) is false but reason (R) is true. Questions: 1. Assertion : Camphor disappears without leaving any residue. Reason : Camphor undergoes sublimation. (1 Point) Option a Option b Option c Option d 2. Assertion : Liquids diffuse easily as compared to gases. Reason : Inter molecular forces are greater in liquids. (1 Point) Option a Option b Option c Option d 3.Assertion : There is no change in the temperature of a substance when it undergoes a change of state through it is still being heated. Reason : The heat supplied is absorbed either as latent heat of fusion or as latent heat of vaporization. (1 Point) Option a Option b Option c Option d 4.Assertion : During evaporation of liquids, the temperature remains unaffected. Reason : Kinetic energy of the molecules is directly proportional to temperature. (1 Point) Option a Option b Option c Option d 5.Assertion : It is easier to cook food at high altitudes. Reason : The boiling point of water decreases at high altitudes. (1 Point) Option a Option b Option c Option d 6.Assertion : A gas can be easily compressed by applying pressure. Reason : Since the inter-particle spaces in the gaseous state are very small, they cannot be decreased by applying pressure. (1 Point) Option a Option b Option c Option d 7.Assertion : The inter molecular forces in solid state are stronger than those in the liquid state. Reason : The space between the particles of matter is called inter molecular space. (1 Point) Option a Option b Option c Option d 8.Assertion : When a beam of light is passed through a colloidal solution placed in a dark place the path of the beam becomes visible. Reason : Light gets scattered by the colloidal particles. (1 Point) Option a Option b Option c Option d 9.Assertion : A solution of table salt in a glass of water is homogeneous. Reason : A solution having different composition throughout is homogeneous. (1 Point) Option a Option b Option c Option d 10.Assertion : A true solution do not exhibits Tyndall effect. Reason : A true solution is a heterogeneous mixture.Immersive Reader (1 Point) Option a Option b Option c Option d
Answer:
1) A
2) D
3) A
4) B
5) D
6) C
7) B
8) A
9) C
10) C
Explanation:
Sublimation refers to the direct change of a substance from solid to gas without passing through a liquid stage. Hence if camphor changes directly from solid to gas, camphor is a sublime substance.
Gases have a higher rate of diffusion than liquids because liquids have greater intermolecular forces while the intermolecular forces in a gas is negligible.
When a substance is heated, a point comes in which heat is supplied but the temperature of the body does not change. This is the point of phase change and the heat supplied at this point may be referred to as latent heat of fusion or vaporization depending on the particular process going on.
While it is true that evaporation occurs at all temperatures and the kinetic energy of molecules is directly proportional to the temperature of a body but the later statement does not explain the former. Rather evaporation occurs because some particles at the surface of the liquid are more energetic and escape due to unbalanced attractive forces acting on them.
Due to decrease in temperature, it takes a longer time to cook food at high altitudes but a lesser time to boil water at higher altitudes.
Gases are easily compressible by applying pressure because gases occupy negligible volume compared to the volume of the container. There is a significant inter particle space between gas particles.
The solid state contains the strongest degree of intermolecular forces. However, the reason offered, though correct, is not the correct explanation of the assertion stated.
This is the Tyndall effect. Colloidal particles scatter light rays and the path of the light becomes visible in the colloidal solution.
Salt solution is homogeneous. A homogeneous solution contains only one phase throughout. If it has a different composition, the solution is heterogeneous. Hence the explanation is false.
A true solution will not exhibit Tyndall effect because the particles are less than colloidal size. A true solution cannot be a heterogenous mixture hence the reason is false.
What volume of 18.0 M H2SO4 is needed to contain 2.45 moles of H2SO4?
Answer:
0.136 L = 136 mL
Explanation:
18.0M = 18.0 mol/L
2.45 mol /(18.0 mol/L) = 0.136 L = 136 mL
Un recipiente de 3L lo llenamos de O 2 a 10°Cy 740 mm de presión cuantos gramos se introduce? cuantos moles? cual densidad? ¿Cuál debería ser la temperatura para que la presión se redujera a la mitad?
Answer:
Ve explicación abajo
Explanation:
Responderemos esta pregunta en dos partes.
PAra la primera parte, usaremos la expresión de gases ideales la cual es:
PV = nRT (1)
Donde:
P: Presión (atm)
V: Volumen (L)
n: moles
R: constante universal de gases (0.082 L atm/ mol K)
T: Temperatura (K)
En este caso, tenemos un recipiente que se llena completamente de oxígeno (O₂) hasta 3 L. Este sería su volumen. a la presión de 740 mmHg, esta es la presión y debemos convertirla a atmosfera, y la temperatura de 10 °C que debe ser convertida a Kelvin. Con esos datos se puede calcular primero los moles de oxigeno y luego los gramos.
Transformando las unidades de presión y temperatura tenemos:
P = 740 mmHg * 1 atm / 760 mmHg = 0.974 atm
T = 10 + 273 = 283 K
Con estos datos, usaremos la expresión (1) para calcular los moles:
n = PV / RT
n = 0.974 * 3 / 0.082 * 283
n = 0.1259 moles
Con estos moles, se pueden calcular los gramos usando el peso molecular del oxigeno que es 16 g/mol. (Como tenemos 2 atomos, serían 32 g/mol):
m = n * PM
m = 0.1259 * 32
m = 4.0288 g
Ahora que tenemos la masa se puede calcular la densidad con la siguiente expresión:
d = m/V
Usando el volumen en mililitros (3 * 1000 = 3000 mL) y la masa obtenida, calculamos entonces la densidad.
d = 4.0288 / 3000
d = 0.00134 g/mL
Para la segunda y ultima parte del ejercicio, usaremos la ley de boyle donde se mantiene el volumen constante (en este caso 3 L) y solo se altera presión y temperatura. De esta forma calcularemos la temperatura necesaria para que la presión se reduzca a la mitad:
P₁/T₁ = P₂/T₂
Y queremos saber es la temperatura para que la presión sea la mitad de la presión inicial, por tanto:
P₂ = 1/2P₁
Sabiendo que la temperatura es de 10 °C (283 K) tenemos entonces:
P₁/T₁ = P₁/2T₂ Se cancelan las presiones y nos queda
1/T₁ = 1/2T₂
2T₂ = T₁
T₂ = 1/2T₁
Reemplazando la temperatura:
T₂ = 283 / 2
T₂ = 141.5 K