Many chemistry questions, acid and bases, stoichiometry
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Note:
1. Please clearly show all steps of logical solutions.
2. Be sure to give answers correct units and significant figures.
1.True or false
A. All compounds that contain hydrogen are acids.
B. A solution with pH 5 has 10 times higher [H+] than a solution with
pH 6.
C. SO3 in the atmosphere is one cause of acid rain.
D. Agricultural fertilizers are not a cause of water pollution.
E. One function of an auto catalytic converter is to convert CO
to CO2
F. In two half lives a radioactive isotope is completely gone.
G Beta radiation from an atom is emission of a valence electron.
H. In the same size container at the same temperature, 25g of N2 gas
Has the same pressure as 25g of NH3 gas.
I. Chlorofluorocarbon compounds are considered to be a prime cause
of ozone depletion in the stratosphere..
J. The two elements in greatest amount in air are N2 and O2 .
2. A water solution has 1.00x10-3 moles of H+ in 10.0L of solution.
A. What is the [H+] ?
B. What is the pH ?
C. What is [OH-] ?
D.Is the solution acidic or basic?
3. Explaining the reasons for your answers:
A. Why is a solution of SO3 in water acidic?
B. Why is a solution of MgO in water basic?
4. A. An isotope with atomic number 89 and mass number 225 emits an alpha
particle. What are the atomic and mass numbers of the resultant atom?
B. An isotope with atomic number 74 and a mass number of 188 emits a beta particle. What are the atomic and mass numbers of the resultant atom?
5. What is the pressure in atmospheres of 125 grams of N2 gas in a 12.0L container at 25.0oC ?
6. Why is HCl termed a "strong acid" and CH3COOH termed a "weak" acid?
7. How many grams of NaOH are contained in 825mL of a 0.400 molar solution?
8. 2C8H18 + 25O2 ? 16CO2 + 18H2O
How many liters of CO2 gas result at 0.950atm and 25.0oC when 525g of C8H18 react ?
9. Person A has well water with 0.011ppm (parts per million) of Pb2+ Person B has well water with 6.5x10-5 grams of Pb2+ in 5.00L
Which person has well water with the lower concentration of Pb2+ ? Clearly explain the reason for your answer.
10. 975 atoms of an element with a half life of 4.50 seconds are synthesized. How many of the atoms remain
A. After 9.00 seconds?
B. After 13.50 seconds?
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Solution Summary
This problem contains the answers to 15 stoichiometry and acid/base problems as well as 10 true and false questions pertaining to chemistry concepts. Clear explanations are delivered for most of the true/false problems, and all math is given in step-by-step detail. If any of these questions is giving you trouble, be sure to download this solution for some expert help!
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1.True or false
A. All compounds that contain hydrogen are acids.
---FALSE, because you can name a litany of compounds with hydrogen (methane, water, etc) that are not particularly acidic
B. A solution with pH 5 has 10 times higher [H+] than a solution with pH 6.
--TRUE, pH is a log scale, so every point is a 10-fold change in H+ concentration
C. SO3 in the atmosphere is one cause of acid rain.
--TRUE, SO3 can react with water to form sulfuric acid in weak concentrations
D. Agricultural fertilizers are not a cause of water pollution.
--FALSE, The nitrates in the fertilizers can leach out with the rain and flow into water sources if not applied carefully
E. One function of an auto catalytic converter is to convert CO
to CO2
--TRUE
F. In two half lives a radioactive isotope is completely gone.
--FALSE, Two half-lives would reduce the amount of isotope to 1/4 the original amount
G Beta radiation from an atom is emission of a valence electron.
--TRUE
H. In the same size container at the same temperature, 25g of N2 gas
Has the same pressure as 25g of NH3 gas.
--FALSE, 25g of N2 is a little less than 1 mol, while 25g of NH3 is nearly 2 moles of gas, so the amounts in molar terms are different
I. Chlorofluorocarbon compounds are considered to be a prime cause
of ozone depletion in the stratosphere..
--TRUE, this is why CFCs are not regularly used as refrigerants any longer
J. The two elements in greatest amount in air are N2 and O2 .
--TRUE taken together O2 and N2 occupy more than 98% of all gas in the atmosphere
2. A water solution has 1.00x10-3 moles of H+ in 10.0L of solution.
A. What is the [H+] ?
1.00x10^-3 mol in 10 L is 1.00x10^-4M
B. What is the pH ?
-log[H+]=pH
-log(1e-4) =4
pH=4
C. What is [OH-] ?
pH+pOH = 14
4+pOH=14
pOH=10
-log[OH-] = pOH=10
Solve for OH-
[OH-] = ...
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