Answer:
Explanation:
Dmitri Mendeleev was a Russian scientist that proposed the first periodic table of elements. Elements in his periodic table were arranged according to there relative atomic mass; however cobalt (Co) with an atomic mass of 58.93 was placed before nickel (Ni) with an atomic mass of 58.69 which was an anomaly as according to his law, nickel should come before cobalt since nickel has a lesser mass compared to cobalt.
A volume of 500.0 mL500.0 mL of 0.140 M0.140 M NaOHNaOH is added to 585 mL585 mL of 0.200 M0.200 M weak acid (Ka=4.71×10−5).(Ka=4.71×10−5). What is the pHpH of the resulting buffer?
Answer:
pH = 4.50
Explanation:
A weak acid HX reacts with NaOH as follows:
HX + NaOH → H2O + NaX
Initial moles of HX are:
0.585L * (0.200mol / L) = 0.117 moles of HX
The moles of NaOH are moles of NaX that are produced, that means:
0.500L * (0.140mol / L) = 0.07 moles of NaOH = 0.070 moles of NaX produced.
And moles of HX that still in solution are:
0.117 moles - 0.070 moles = 0.047 moles of HX
To find the pH of this buffer (Mixture of a weak acid, HX with its conjugate base, NaX) we use H-H equation:
pH = pKa + log [NaX] / [HX]
Where pKa is -log Ka = 4.327
And [] could be taken as moles of each species.
Replacing:
pH = 4.327 + log [0.070] / [0.047]
pH = 4.50
how many moles of oxygen gas can 0.88 mole of hydrogen
Answer:
0.44 mole of oxygen gas can 0.88 mole of hydrogen peroxide (h2o2) produce, if decomposition is complete.
time equals distance divided by
If a sample contains 78.0 % of the R enantiomer and 22.0 % of the S enantiomer, what is the enantiomeric excess of the mixture?
Answer: The enantiomeric excess of the mixture =56%
Explanation:
As per given : R isomer = 78%
S isomer = 22%
In chiral substances, Enantiomeric excess is the measure of purity.
So, Enantiomeric excess of the mixture = [tex]|\frac{R-S}{R+S}|\times100[/tex]
[tex]=|\frac{78-22}{78+22}|\times100[/tex]
[tex]=|\frac{56}{100}|\times100\% \\\\=56\%[/tex]
Hence, the enantiomeric excess of the mixture =56%
In what ways is a model similar to the thing it represents?
A. A model must be identical to the thing it represents in every way.
B. model can be different from the thing it represents in either its size or the materials it is made of.
C. A model must be identical to the thing it represents in every way except that it can be made out of different materials.
D. A model must be identical to the thing it represents in every way except that it can be a different size.
Answer: A
Explanation: A model has to be identical to the thing it represents in every way, or people may think something is different than it actually is, because they see it in the model. The answer to the question is A.
Please solve the Problems below and round to the correct sig figs:
1. 0.961 - 0.07
2. 0.961 - 0.0700
3. 540.0 X 2.02
4. 540 x 2.02
Answer:
1. 0.891
2. 0.891
3. 1,090.8
4. 1,090.8
Explanation:
Which is a product of nuclear fusion?
A a nucleus that has a greater mass number than the starting materials
B two nuclei that are roughly half the mass of the starting materials
C a nucleus that has the same atomic number as the starting materials
D two nuclei that have greater atomic numbers than the starting materials
Answer:
A. a nucleus that has a greater mass number than the starting materials
Explanation:
The statement is "a nucleus that has a greater mass number than the starting materials."
What is nuclear fusion?Nuclear fusion occurs when two or more atomic nuclei unite to generate one or more new atomic nuclei and subatomic particles.
Two light nuclei fuse to form a single heavy nucleus in a fusion reaction. Because the overall mass of the resulting single nucleus is smaller than the mass of the two initial nuclei, the process releases energy.
Hence, the correct option is A
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how many electrons are in as3-
is it true that a gas takes up the shape of the container
The image shows four organelles: which of these controls what enters and exits the cell?
Answer:
The cell membrane.
Explanation:
Please awnser asap!!! 20 points!!
According to the law of conservation of mass, how many hydrogen and chlorine atoms are required for this reaction?
A 1 hydrogen atom and 1 chlorine atom
B 1 hydrogen atom and 2 chlorine atoms
C 2 hydrogen atoms and 1 chlorine atom
D 2 hydrogen atoms and 2 chlorine atoms
Answer: d
Explanation:
Did this last year
A 3.458 g sample of KHP, a monoprotic acid, requires 45.71 mL of a KOH solution to reach the endpoint. What is the concentration of the KOH solution
Answer:
0.3704M is the concentration of KOH
Explanation:
The reaction of the monoprotic acid, KHP, with KOH is:
KHP + KOH → H₂O + K₂P
An acid reacts with a base to produce water and a salt
The molar mass of KHP is 204.22g/mol, that means in 3.458g of KHP you have:
3.458g * (1mol / 204.22g) = 0.01693 moles KHP.
At the endpoint:
Moles KHP = Moles KOH. That means moles KOH Are 0.01693 moles. These moles are in 45.71mL = 0.04571L, the molar concentration is:
0.01693 moles KOH / 0.04571L =
0.3704M is the concentration of KOHThe concentration of the KOH solution needed for the reaction is 0.370 M.
We'll begin by calculating the number of mole in 3.458 g of KHP. This can be obtained as follow:
NOTE:KHP => Potassium hydrogen phthalate
Mass of KHP = 3.458 g
Molar mass of KHP = 204.22 g/mol
Mole of KHP =?Mole = mass / molar mass
Mole of KHP = 3.458 / 204.22
Mole of KHP = 0.0169 mole Next, we shall determine the number of mole of KOH needed to react with 0.0169 mole of KHP. This can be obtained as follow:KHP + KOH → H₂O + K₂P
From the balanced equation above,
1 mole of KHP reacted with 1 mole of KOH.
Therefore,
0.0169 mole of KHP will also react with 0.0169 mole of KOH to the end point.
Finally, we shall determine concentration of the KOH solution. This can be obtained as follow:Mole of KOH = 0.0169 mole
Volume = 45.71 mL = 45.71 / 1000 = 0.04571 L
Concentration of KOH =?Concentration = mole / Volume
Concentration of KOH = 0.0169 / 0.04571
Concentration of KOH = 0.370 MTherefore, the concentration of the KOH solution needed for the reaction is 0.370 M
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What is the shape of the hypothetical molecule XY3
Answer:
Trigonal planar
Explanation:
If a hypothetical molecule XY3 has three electron domains as shown and no lone pairs, the molecule will be trigonal planar in shape.
From the valence shell electron pair repulsion theory, the shape of molecules is dependent on the number of electron domains in a molecule and weather those electron pairs are lone pairs or bond pairs.
Since lone pairs cause more repulsion and take up more space around the central atom than bond pairs, bond pairs cause the bond angle and molecular geometry to deviate from that predicted on the basis of the valence shell electron pair repulsion theory.
Finally, remember that in a molecule, electron pairs are placed as far apart in space as possible to minimize repulsion.
What is the mass number of an atom with 17 protons, 17 electrons,and 18 nuetrons?
Answer:
35
Explanation:
the formula is: mass number = protons + neutrons
so 17+18=35
Using the information in the table to the right, calculate the average atomic mass of copper. Report to two decimal places.
Answer: 63.55 amu
Answer:63.55
Explanation:
What is the order of a reaction with a half-life that is directly proportional to initial concentration? Select the correct answer below: Zero order First order Second order None of the above
Answer:
Zero order
Explanation:
A zero order reaction is one in which the rate of reaction is independent of the concentration of reactants.
In a zero-order reaction, the half-life of the reactants is directly proportional to the initial concentration of the reactants . As initial concentration increases, the half-life for the reaction increases likewise and vice versa.
Compare the density of nitrogen gas to the density of argon gas when both gases are at 298 K and 101.3 kPa.
Answer:
Ar = 1.63g/L; N₂ = 1.14g/L. The density of Argon is higher than density of nitrogen because molar mass of argon > Molar mass nitrogen
Explanation:
It is possible to obtain the density of a gas using the formula:
ρ = PM / RT
Where ρ is density in g/L
P is pressure of the gas (101.3kPa)
M is molar mass of the gas (Ar: 39.9g/mol; N₂: 28g/mol)
R is gas constant (8.314kPaL/Kmol)
And T is temperature (298K)
Thus, density of Ar and N₂ is:
Ar = 101.3kPa*39.9g/mol / 8.314kPaL/Kmol*298K
Ar = 1.63g/L
N₂ = 101.3kPa*28g/mol / 8.314kPaL/Kmol*298K
N₂ = 1.14g/L
As general rule, under the same conditions, the gas with the higher molar mass will be the gas with higher density.
The argon gas will have greater density when compared to nitrogen gas in the given condition.
The given parameters;
temperature of the gases, T = 298 Kpressure of the gases, P = 101.3 kPaThe ideal gas law can be used to determine the density of the gases;
[tex]PV = nRT\\\\PV = \frac{m}{M} RT\\\\PM = \frac{m}{V} RT\\\\PM = \rho RT\\\\\rho = \frac{PM}{RT}[/tex]
where;
M is the molar mass of the gasesR is ideal gas constantThe molar mass of nitrogen gas is given as;
M = 14 g/mol
The molar mass of argon gas is given as;
M = 40 g/mol
From the formula given above, we can conclude that the gas with greater molar mass will have greater density, in this case the argon gas will have greater density when compared to nitrogen gas in the same condition.
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ITS DUE IN 12 MINUTES PLEASE HELP ME :((
1. Fog is an example of aerosols true or false
Answer:
true?
Explanation:
stion 1/2 Which of the following is a physical property?
A. The boiling point o a certain alcohol is 78 degrees Celsius
B. Diamond is very hard
C. Sugar ferments to form alcohol
D. A metal wire conducts an electric current
HELP ASAP You have a mixture of water, alcohol, and iron. Tell me, how would you separate them from each other?
Answer:
Put them on boiling wtaer, and they will sart to seperate
Explanation:
A student completed the lab but found that the total amount of material recovered weighed more than the original sample. What is the error?
Answer:
Throughout the description section elsewhere here, the interpretation as per the particular circumstance is defined.
Explanation:
Sources of error become basically factors of measurement uncertainty. If the cumulative volume of retrieved material weighed almost as much as the initial sample, and therefore procedural cause of error is still much most probable.Lost compound will be:
= [tex]454-122[/tex]
= [tex]332[/tex]
Percentage of the lost compound will be:
= [tex]\frac{332}{454}\times 100[/tex]
= [tex]73.13 \ percent[/tex]
Bornite is which type of ore?
O iron ore
O bauxite ore
Ouraninite ore
O copper ore
Answer:
O copper ore
Explanation:
Answer:
a rock that contains enough of a metal to be worthwhile to extract
Explanation:
At what pressure would a 0.175 mole sample of gas at 22.0°C have a volume of 2175
mL?
Answer:
[tex]P=1.95atm[/tex]
Explanation:
Hello!
In this case, since we are asked to compute the pressure of 0.175 moles of the given gas at 22.0 °C occupying a volume of 2175 mL, we can use the ideal gas equation as shown below:
[tex]PV=nRT[/tex]
Whereas our unknown is P and we solve for it as shown below:
[tex]P=\frac{nRT}{V}\\ \\P=\frac{0.175mol*0.082\frac{atm*L}{mol*K}*(22.0+273.15)K}{2175mL*\frac{1L}{1000mL} }\\ \\P=1.95atm[/tex]
Take into account that based on the given R units, the temperature must be in Kelvins and the volume in liters.
Best regards!
Volcanologists are scientists who study volcanic eruptions. However, most volcanologists rarely get to witness a volcanic eruptions actually occurring. Instead, many volcanologists use models to study volcanic eruptions. What is the most likely reason why volcanologists often rely on models to study volcanic eruptions?
A.
Volcanic eruptions are too large to be able to see with the naked eye.
B.
Volcanic eruptions are very dangerous events.
C.
Volcanic eruptions are rare occurrences so it is difficult to see them.
D.
Volcanic eruptions take too long to be able to be observed in their entirety.
Answer:
Volcanic Eruptions are a very dangerous event
Explanation:
Models represent objects, events, and processes in the real world. Models are often used when an object, event, or process occurs too slowly or too quickly; is too small or too large; is too complicated or too dangerous. Volcanic eruptions produce both molten lava and poisonous gases. Therefore, eruptions can be very dangerous. Many volcanologists have lost their lives while observing volcanic eruptions.
Are homogeneous mixtures only able to be chemically separated into their own individual components?
Answer:
Are the components of a homogeneous mixture are chemically combined?
Mixtures are physically combined structures that can be separated into their original components. A chemical substance is composed of one type of atom or molecule. ... A homogeneous mixture is a type of mixture in which the composition is uniform and every part of the solution has the same properties.
Explanation:
How many grams of a 15.6% sugar solution contain 40.0 g of sugar?
Choose all the answers that apply.
DNA contains coded information for _____.
hibernation
body structure
eye color
height
photosynthesis
Answer: Hibernation, Eye color and height
Explanation: DNA is the most important molecule of life. Many behaviors are controlled by DNA, such as telling bears how long to hibernate. All of the physical and chemical characteristics of an organism are also controlled by DNA, some cells will form bone, While others will form skin, hair and lungs.
20 points!!! PLEASE AWNSER ASAP!!!
A copper wire was cut into pieces and dropped into a test tube containing acid, Bubbles formed immediately, the liquid in the test tube turned green, and the pieces of wire were no longer visible, which most likely happened to the pieces of copper wire?
А. The copper wire was chemically changed when it was cut and placed in the acid,
B the copper wire was physically changed when it was cut and placed in the acid,
C The copper wire was physically changed when it was cut and chemically changed when it was placed in the acid,
D The copper wire was chemically changed when it was cut and physically changed when it was placed in the acid,
Answer: i think its A
Explanation:
Answer:
A
Explanation:
Becuase bubbles only come from chemical changes
6. A gas occupies a volume of 125.0 mL at 10.0C. At what temperature would the volume be 50.0 mL?
Answer:
V1= 125.0mL 125.0mL/10.0C=50.0mL/T2
T1= 10.0C T2=(125.0mL/10.0C) X 50.0mL
V2= 50.0mL T2= 625L
T2=?
Explanation:
I'm pretty sure about this It took me a while to get it but I already took the test