Answer: This means that the isotope of silicon with a mass number of 28 is by far the most common of these three isotopes.
Explanation:
The abundance of Si-28 is 92.23%. Si-29 is 4.68% and Si-30 is 3.09%.
If the molar absorptivities of HIn and In- were determined at a wavelength corresponding to an isosbestic point, how would they compare in value
Answer:
A Weak acid indicator has general formulae HIn- and base has In-.
When constructed a plot determining wavelength equilibrium reached according to the equation HIn(aq) + H2O(l) ↔ In-(aq) + H3O+(aq)
HIn(aq) is the acid, that has a different color from the base In-(aq). When the pH is low, the concentration of the hydronium ion H3O+ is high and equilibrium is toward the left, producing the color A.
At high pH, the concentration of H3O+ is low, so equilibrium tends toward the right side of the equation and color B is displayed
A student mixed 25 grams of salt into 1,000 grams of water.
What is the mass of the mixture?
A. 975 grams
B. 1,000 grams
C. 1,025 grams
D. 2,500 grams
The two main postulates that was given by Antoine Lavoisier are, oxygen play an important role in combustion and the other is mass of reaction is always conserved. Therefore, the mass of the mixture is 1025g. the correct option is option C.
What is law of conservation of mass?According to Law of conservation of mass, mass can neither be created nor be destroyed. Mass can only be transformed from one form to another. The law of conservation of mass was given by Antoine Lavoisier. Every reaction in nature follow the law given by Antoine Lavoisier that is mass is always conserved.
mass of salt+ mass of water=mass of solution
mass of salt =25 grams
mass of water=1,000 grams
substituting the given values, we get
25 grams+ 1,000 grams =mass of solution
mass of solution=1025g
Therefore, the mass of the mixture is 1025g. the correct option is option C.
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Which of the following questions about the flu is a scientific question?
A. Is a flu shot effective in preventing the flu?
B. Is public fear of the flu out of control?
C. Is the benefit of drugs for the flu higher than the cost?
D. Who should receive a flu shot if there is not enough flu vaccine for
everyone?
Answer:
A is the correct answer
Explanation:
One method for removing hydrogen sulfide impurities from natural gas is by its reaction with oxygen at high temperatures to form sulfur and water vapor. After balancing the following equation, determine the coefficient in front of the reactant O2. H2S(g) + O2(g) → S8(l) + H2O(g) Group of answer choices
Answer:
4
Explanation:
H2S(g) + O2(g) → S8(l) + H2O(g)
Upon balancing the equation;
8H2S(g) + 4O2(g) → S8(l) + 8H2O(g)
The coefficient of O2 in the reaction above is 4.
The interaction of water droplets in rain with carbon dioxide that is naturally present in the atmosphere causes rain water to be slightly acidic because CO2 is an acidic anhydride. As a result, pure clean rain has a pH of about 5.7. What are the hydrogen ion and hydroxide ion concentration in this rain water
Answer:
Explanation:
pH = 5.7
- log [ H⁺ ] = 5.7
[ H⁻ ] = 10⁻⁵°⁷ M
= 2 x 10⁻⁶ M
[ H⁺ ] x [ OH⁻ ] = 10⁻¹⁴
2 x 10⁻⁶ x [ OH⁻ ] = 10⁻¹⁴
[ OH⁻ ] = .5 x 10⁻⁸ M
= 5 x 10⁻⁹ M
An aqueous solution contains 0.22 M ammonium iodide. One liter of this solution could be converted into a buffer by the addition of:
Answer:
The addition of NH₃⁺
Explanation:
A buffer is an aqueous mixture of a weak acid and its conjugate base or vice versa.
In ammonium iodide, NH₄I, the ions in solution are ammonium ion, NH₄⁺ and iodide ion, I⁻.
The iodide ion is the conjugate base of the HI, a STRONG ACID, that means the addition of HI in solution wouldn't produce a buffer.
And, NH₄⁺ is the conjugate acid of the NH₃, a WEAK BASE, that means the addition of NH₃ to the solution will produce a buffer: The mixture of a weak base, NH₃ and its conjugate acid, NH₄⁺
1. How are chemical bonds formed? *
Answer: Bonds form when atoms share or transfer valence electrons. Valence electrons are the electrons in the outer energy level of an atom that may be involved in chemical interactions. Valence electrons are the basis of all chemical bonds.
Explanation: Due to atoms and science ;)
Answer:
throught transferring or sharing an electron
Explanation:
a p e x :)))
I have 5.33 moles of helium gas at 1.56 atm and a temperature of 25 ° C. What is the volume of my helium sample? 
Answer:
V = 83.6 L
Explanation:
Given data:
Number of moles of He = 5.33 mol
Pressure of gas = 1.56 atm
Temperature of gas = 25°C
Volume of sample = ?
Solution:
Formula:
PV = nRT
P= Pressure
V = volume
n = number of moles
R = general gas constant = 0.0821 atm.L/ mol.K
T = temperature in kelvin
Now we will convert the temperature.
25+273 = 298 K
Now we will put the values in formula.
1.56 atm × V = 5.33 mol × 0.0821 atm.L/ mol.K × 298 K
1.56 atm × V = 130.4 atm.L
V = 130.4 atm.L/1.56 atm
V = 83.6 L
Find the density of an object that has a volume of 2.3 x 10^2 and a mass of
3.5 x 10^3. *
Answer:
[tex]\frac{250}{23}[/tex]
Step-by-step explanation:
[tex]10^{2} = 100[/tex] 2.3 × 100 = 230[tex]10^{3} = 1000[/tex] 3.5 × 1000 = 3500[tex]D = \frac{m}{v}[/tex] [tex]D = \frac{3500}{230}[/tex] 3500 ÷ 230 = [tex]\frac{250}{23}[/tex]I hope this helps!
In his 1859 book On the Origin of Species, Charles Darwin stated
that modern organisms have evolved from common ancestors
through he process of
d
O adaptation
O evolution
diversification
O natural selection
pls help
natural selection
Explanation:
The hydrolysis of sucrose (C12H22O11) into glucose and fructose in acidic water has a rate constant of 1.8×10−4s−1 at 25 ∘C. Assuming the reaction is first order in sucrose, determine the mass of sucrose that is hydrolyzed when 2.45 L of a 0.170 M sucrose solution is allowed to react for 195 min.
Answer:
Explanation:
k = 1.8 x 10⁻⁴ s⁻¹
no of moles initially = 2.45 x .17 = .4165 moles
initial moles a = .4165
k = (1 / t ) ln a / ( a - x )
a is initial moles , x is moles reacted .
a is initial moles , x is moles reacted .
time t = 195 min = 11700 s
1.8 x 10⁻⁴ = 1 / 11700 x ln .4165 /( .4165 - x )
2.106 = ln .4165 /( .4165 - x )
.4165 /( .4165 - x ) = e²°¹⁰⁶ = 8.215
.4165 = 3.42 - 8.215 x
8.215 x = 3.0035
x = .3656
moles of sucrose hydrolysed = .3656 moles.
- On a test, Helena is defining energy. Which must she include in order to get her answer marked correct?
○making objects more compact
O the ability to do work
O carrying through matter and space
O the bonds of atoms
Answer: Option 2, The ability to do work.
Explanation: Edge
Energy can be defined as:
B. the ability to do work, It can of many forms.
What is Energy?Energy is the capacity of an item to take care of business. It might exist in potential, motor, warm, electrical, substance, atomic, or other different structures. As per the work-energy hypothesis, the work done is put away in the energy of the body.
Thus, option B is correct.
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How many Joules are required to change 30.0g ofice at -20°C to steam at 140°C? There are a few steps you should follow using the following given
information
• The specific heat of ice is 2.108 J/g*°C
• The specific heat of water is 4.18 J/g*°C
• The specific heat of steam is 2.010 J/g*°C
• Hf for H2O = 334 334 J/g
• Hv for H2O = 2260 J/g
Answer:
Q = 10118.4 j
Explanation:
Given data:
Mass of ice = 30.0 g
Initial temperature of ice = -20°C
Final temperature = 140°C
Energy required = ?
Solution:
The specific heat of ice is 2.108 J/g*°C
Formula:
Q = m.c. ΔT
Q = amount of heat absorbed or released
m = mass of given substance
c = specific heat capacity of substance
ΔT = change in temperature
ΔT = 140°C - (-20°C)
ΔT = 160°C
Q = 30.0 g× 2.108 J/g°C ×160°C
Q = 10118.4 j
A hypothetical element consists of two isotopes of masses 69.95 amu and 71.95 amu with abundances of 25.7% and 74.3%, respectively. What is the average atomic mass of this element?
a. 71.95 amu
b 71.4 amu
c. 69.95 amu
d. 70.95 amu
e. 70.5 amu
Answer:
Option B. 71.4 amu
Explanation:
From the question given above, the following data were obtained:
Isotope A:
Mass of A = 69.95 amu
Abundance (A%) = 25.7%
Isotope B:
Mass of B = 71.95 amu
Abundance (B%) = 74.3%
Average atomic mass =..?
The average atomic mass of the element can be obtained as shown below:
Average atomic mass = [(Mass of A × A%)/100)] + [(Mass of B × B%)/100)]
= [(69.95 × 25.7)/100] + [(71.95 × 74.3)/100]
= 17.977 + 53.459
= 71.436 ≈ 71.4 amu
Therefore, the average atomic mass of the element is 71.4 amu
g Part A A Hofmann degradation of a primary amine forms an alkene that gives butanal and 2-methylpropanal upon ozonolysis and workup under reducing conditions. Identify the amine.
Answer:
Explanation:
When the primary amine undergoes Hofmann degradation it forms an Alkene
In this case the alkenes have undergone ozonolysis and has formed two products as butanal and 2-methyl propanal
when we revert back from these aldehydes to alkene we observed the alkene formed will be "2-methyl hept-3-ene " this alkene is the Hofmann product of that primary amine
upon addition of this alkene we observe the primary amine formed is
4-amino-2-methylheptane
If the analysis of carbon in a molecule indicates sp hybridization, what must be the shape around the carbon
Answer:
The shape around the carbon is linear . Sp hybridisation generally tends to be linear.
Explanation:
The hybridization procedure includes blending of the valence s orbital with one of the valence p orbitals to yield equal sp hybrid orbitals which can be orientated in a linear geometry. The p orbital is one orbital that could keep up to 2 electrons. The sp set is equal orbitals that factor 180° from every other.
Hence , the answer is linear shape around the carbon.
when the tempature of the enviroment changes, the body tempature of a reptile
The atoms of which element will form cations?
A. selenium
B. neon
C. copper
D. iodine
Answer Copper, copper is a type of metal, so it can form cations
The atoms of element will form cations is Copper as to get the stable electronic configuration.
What are cations?
Cations are those species which carries possitive charge on it and produced by any element by lossing of their outermost electrons.
An atom will form cation to get the stable outermost configuration.
Selenium belongs from the oxygen group and in the outermost shell 6 electrons are present, so it shows the negative oxidation state as it accepts the two electron to get the stable configuration and form an anion.Neon belongs from the noble gas group which already have stable configuration, so it does not form any cation or anion.Iodine belongs from the halogen groups, and in the outermost shell 7 electrons are present, so it shows the negative oxidation state as it accepts the one electron to get the stable configuration and form an anion.Copper is a transition metal atom and it has 4s¹3d¹⁰ electronic configuration, so it will loss 1 electron from the outermost shell and will form cation.Hence option (C) is correct i.e. Copper.
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Movement of earths tectonic plates appears to be caused by
Aqueous hydrochloric acid will react with solid sodium hydroxide to produce aqueous sodium chloride and liquid water . Suppose 30.3 g of hydrochloric acid is mixed with 25. g of sodium hydroxide. Calculate the minimum mass of hydrochloric acid that could be left over by the chemical reaction. Be sure your answer has the correct number of significant digits.
Answer:
[tex]m_{HCl}^{leftover}=7.50g[/tex]
Explanation:
Hello.
In this case, since the undergoing chemical reaction is:
[tex]HCl+NaOH\rightarrow NaCl+H_2O[/tex]
In order to identify the limiting reactant, we compute the available moles of sodium hydroxide (molar mass = 40 g/mol) and the moles of hydrochloric acid consumed by those moles via their 1:1 mole ratio considering the chemical reaction:
[tex]n_{HCl}=25.0gNaOH*\frac{1molNaOH}{40gNaOH} *\frac{1molHCl}{1molNaOH} =0.625molHCl[/tex]
Next, since the molar mass of hydrochloric acid is 36.46 g/mol, we compute the mass of that reactant that is actually consumed:
[tex]m_{HCl}=0.625molHCl*\frac{36.46gHCl}{1molHCl}=22.8gHCl[/tex]
In such a way, the leftover of HCl is:
[tex]m_{HCl}^{leftover}=30.3g-22.8g\\\\m_{HCl}^{leftover}=7.50g[/tex]
Best regards!
For ethane (C2H6), what is the correct framework of the Lewis structure?
The central atoms consist of two hydrogens.
The central atoms consist of two hydrogens and one carbon.
The central atoms consist of one hydrogen and one carbon.
The central atoms consist of two carbons.
Answer: The answer is D. The central atoms consist of two carbons.
Explanation:
Answer:
The central atoms consist of two carbons
Explanation:
Took the test! hope this helps!
PLEASE HELP!!!
Students combine several chemicals and record the observations in their science notebooks. A list of the observed results is given here. • Production of a gas (bubbles) • Phase change (solid to liquid) • A precipitate forms • Change in shape • Crystals dissolving • Heat produced How many of the observations are evidence that a new substance was formed? *
1 point
3
4
5
6
Answer:
3
Explanation:
I have indeed already took the quizzes my friend
Calculate the percentage by mass of lead in Pb(NO3)2. Calculate the percentage by mass of lead in Pb(NO3)2. 65.3 62.6 44.5 71.2 38.6
Answer:
62.6 %
Explanation:
Pb(NO₃)₂ = 207 + 124 = 331 gram
331 gram of lead nitrate contains 207 grams of lead
100 gram of lead nitrate contains
207 x 100 / 331 = 62.6 %
It can be deduced that percentage by mass of lead in Pb(NO₃)₂ is B. 62.6%.
How to calculate the percentage?From the given information, Pb(NO₃)₂ = 207 + 124 = 331 grams.
Therefore, 331 gram of lead nitrate contains 207 grams of lead. It can be deduced that 100 gram of lead nitrate will contain:
= 207 x 100 / 331
= 62.6 %
In conclusion, the correct option is 62.6%.
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For the reaction of Zn (s) with Cu(NO3)3 (aq), write the molecular, complete ionic and net ionic equations.
Answer:
Explanation:
Molecular reaction
Zn + Cu( NO₃ )₂ = Zn( NO₃ )₂ + Cu
Complete reaction
Zn + Cu⁺² + 2 NO₃⁻ = 2 Zn⁺² + 2 NO₃⁻ + Cu
net ionic reaction
Zn + Cu⁺² = Zn⁺² + Cu
What else is produced during the replacement reaction of magnesium and hydrochloric acid? I Will Give Brainiest To who ever gets right
Mg + 2HCl H2 + ________
MgCl2
Mg2Cl2
Mg2Cl
MgCl
Explanation:
In the reaction of magnesium with hydrochloric acid magnesium chloride and hydrogen gas is formed.
Equation -
Mg + 2HCl → MgCl₂ + H₂↑
Therefore,
Option A is correct ✔.
Answer:
Its A
Explanation: Just took the Pre-Unit test
Calculate the formula mass for HFO2
Answer:
The molar mass is 210.49 g/mol
Explanation:
) Chromate/Dichromate Equilibrium. Yellow chromate ion reacts with hydrogen ion to form (by condensation and loss of H2O) the orange dichromate ion:
Answer:
Explanation:
The Chromite ore is used for the production of Chromate/dichromate formation.
[tex]4FeCr2O4 + 8Na2CrO4+7O2 \\[/tex] →[tex]8NaCrO4 +2Fe2O3 +8CO2\\yellow[/tex]
so[tex]Na2CrO4[/tex] is called Chromite ore which is of yellow color.
[tex]Na2CrO4 +2H^+[/tex] → [tex]Na2CrO4 +2Na^+ +H2O[/tex]
[tex]Orange[/tex]
so when sodium chromate is reacted with hydrogen ion it forms sodium dichromate which is of orange color
Now
[tex]Na2Cr2O7+2KCl[/tex]→[tex]K2Cr2O7 + NaCl[/tex]
The chromate and dichromate are interconvertible in aqueous solution depending upon the PH of solution
Acid medium: [tex]Cr2O4^2-[/tex] [tex]2H^+[/tex]→[tex]Cr2O7^2-[/tex][tex]+H2O[/tex]
Base:[tex]Cr2O7^2- +2OH^-[/tex]→ [tex]CrO4^2- +H2O[/tex]
Hence Chromate and dichromate are interconvertible and hold and equilibrium.
please help!! chemistry question
Answer:
9
Explanation:
Answer:
9
because i studied this
Ammonium perchlorate is the solid rocket fuel used by the U.S. Space Shuttle. It reacts with itself to produce nitrogen gas , chlorine gas , oxygen gas , water , and a great deal of energy. What mass of oxygen gas is produced by the reaction of of ammonium perchlorate
Answer:
2.9 g
Explanation:
The computation of the mass of oxygen gas produced is shown below:
As we know that
[tex]2NH_4ClO_4 \rightarrow N_2 + Cl_2 + 2O_2 + 4H_2O[/tex]
Now
The [tex]NH_4ClO_4[/tex] presented in 9.6g = 9.6 g/117.49 g/mol
And, the mole ratio between the [tex]NH_4ClO_4 : H_2O[/tex] is 1 : 2
The moles of [tex]H_2O[/tex] produced is 2 × 9.6 g/117.49 g/mol
So,
Mass of H2O produced is
= 18.015 g/mol × 2 × 9.6 g/117.49 g/mol
= 2.94 g
Calcium oxide reacts with water in a combination reaction to produce calcium hydroxide. A 4.50-g sample of CaO is reacted with 4.34 g of H2O. How many grams of the excess reagent remain after the reaction is complete
Answer:
2.88 g
Explanation:
First, let us look at the balanced equation of the reaction:
[tex]CaO(s) + H_2O (l) --> Ca(OH)_2(s)[/tex]
From the equation, 1 mole of CaO reacts with 1 mole of H2O to produce 1 mole of [tex]Ca(OH)_2[/tex].
mole = mass/molar mass
4.50 g of CaO = 4.50/56.08 = 0.08 mole
4.34 g of H2O = 4.34/18.02 = 0.24 mole
The ratio of moles of CaO and H2O should be 1:1, hence, H2O is in excess.
Excess mole of H2O = 0.24 - 0.08 = 0.16 mole
mass of 0.16 mole of H2O = mole x molar mass = 0.16 x 18.02 = 2.88 g
Therefore, 2.88 g of the excess reagent (water) would remain after the reaction is complete.