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# 6. In a manometer the mercury level at the open ed of the tube

6. In a manometer the mercury level at the open ed of the tube is 215 mm higher than at the closed end of the tube. If the atmospheric pressure is 1 atm, what is the pressure of the gas sample in units of torr?
(Points : 4)
1.28 torr
545 torr
975 torr
215 torr

7. Using Boyle's Law, predict what will happen to the pressure of a gas in a container at constant temperature, if the volume of the container is changed to one-half its original size. (Points : 4)
Nothing will happen to the pressure.
The pressure will be decrease to one-half its original value.
The pressure will increase to twice its original value.

8. A sample of gas is heated. During the heating process, the volume of the gas increases 1.7 times. If the initial temperature of the gas is 80°C, what is the final temperature of the gas? (Points : 4)
136°C
600 K
210 K
353 K

9. Suppose that you have a 2.0 L sample of hydrogen at 1.00 atm and 59°C. If you heat the sample to 84°C and it expands to a volume of 3.7 L, what will the final pressure be? (Points : 4)
0.58 atm
0.76 atm
0.54 atm
1.00 atm

10. A helium balloon with a volume of 2.4 L contains 0.10 moles of gas at 25°C and 1 atm of pressure. The balloon leaks 0.02 moles of gas until someone manages to seal the hole. What is the new volume of the balloon? (Points : 4)
3.0 L
0.5 L
19.2 L
2 L

11. There is an unlabeled gas cylinder in the chemistry lab. The cylinder contains a gaseous compound. A sample of the compound shows that it contains 27.27% carbon and 72.73% oxygen. The 1.50 L bottle was found at STP and contained 2.94 g of the compound. Identify the number of moles of the compound in the bottle. (Points : 4)
1.96 mol
0.0669 mol
0.105 mol
0.0609 mol

12. Two gas tanks are linked by a connecting tube of negligible volume with a valve. One contains 15 L of nitrogen at 7.2 atm of pressure. The other contains 8.3 L of helium at 4.1 atm of pressure. If the valve is opened, what is the final pressure of the two tanks combined? (Points : 4)
142 atm
4.5 atm
6.1 atm
0.48 atm

13. Which of the following steps illustrates work being done? (Points : 4)
A beaker of water being heated from 25°C to 75°C.
A battery producing 1.5 V.
A box being pushed up a ramp.
A log burning in a fireplace.

14. Which of the following has the highest number of Calories? (Points : 4)
7.2 g of fat
9.8 g of starch
15.5 g of sugar
14.3 g protein

15. What is the sign of q when heat moves from the surroundings to the system? (Points : 4)
It depends on the value of work.
Positive
Negative
This situation never occurs.

16. Which of the following is true about an endothermic reaction? (Points : 4)
The reactants have a lower enthalpy than the products.
The reactants have a higher enthalpy than the products.
The reactants have the same enthalpy as the products.

17. For the reaction:

6HCl(aq) + 2Fe(s) --> 2FeCl3(aq) + 3H2(g)

Which of the following rate expressions is NOT correct? (Points : 4)
Rate = -[HCl]/6t
Rate = -[Fe]/2t
Rate = 2[FeCl3]/t
Rate = [H2]/3t

18. The rate equation for the synthesis of water

2H2 + O2 --> 2H2O

is

Rate = k[H2][O2]

What is the overall order of this reaction? (Points : 4)
0
1
2
3

19. The following reaction is second order in [A] and second order overall.

2A --> B + C

The instantaneous rate of reaction is 1.8 × 10-3 M/s when [A] is equal to 0.63 M. What is the rate constant, k, of this reaction? (Points : 4)
1.4 × 10-3 M-1s-1
2.2 × 102 M-1s-1
4.5 × 10-3 M-1s-1
7.1 × 10-4 M-1s-1

20. The activation energy (Ea) on a reaction diagram for an uncatalyzed reaction is generally ________ a catalyzed reaction. (Points : 4)
the same as
unrelated to
greater than
less than

21. In a reaction, the equilibrium constant for the forward reaction is Kf and the equilibrium constant of the backward reaction is Kb. What is the relationship between Kf and Kb? (Points : 4)
Kf = Kb
Kb = 1 + Kf
Kf = 1/Kb

22. (Points : 4)
0.95
1.05
0.2
3.74

23. (Points : 4)
The energy of the system will increase.
More methanol will decompose.
The equilibrium position will not be affected.
More methanol will be formed.

24. A simple dissociation reaction is written for each of the following acids. Which one is least correct? (Points : 4)
Hydrochloric acid:

The ammonium ion:

Acetic acid:

The hydrated aluminum (III) ion:

25. What is the [H3O+] in a solution with a pH of 2.34? (Points : 4)
4.57 x 10-3 M
4.6 x 10-3 M
4.57 x 103 M
4.6 x 103 M

26. A 0.200 M solution of a weak acid, HA, is 9.4% ionized. Using this information, calculate Ka for HA. (Points : 4)
1.8 x 10-3
3.8 x 10-3
9.4 x 10-3
1.9 x 10-2

27. Which of the following is not a buffer solution? (Points : 4)
a weak acid (to neutralize a strong base) and its conjugate base (to neutralize a strong acid)
a weak base (to neutralize a strong acid) and its conjugate acid (to neutralize a strong base)
a strong acid (to neutralize a strong base) and its conjugate base (to neutralize a strong acid)
formic acid and sodium formate

28. Which statement about alcohols is not correct? (Points : 4)
Alcohols contain hydroxyl functional groups.
Alcohols are organic molecules.
Alcohols contain nitrogen.
Alcohols are named by their Greek prefix
+ -anol.

29. Which of the following shows the alkanes in correct order from lowest to highest boiling points? (Points : 4)
hexane, pentane, butane, propane, ethane, methane
hexane, ethane, propane, butane, pentane, methane
methane, ethane, propane, butane, pentane, hexane
methane, ethane, propane, pentane, butane, hexane

30. Which characteristic defines the main difference between a basic buffer system and an acidic buffer system? (Points : 4)
A basic buffer system uses more base than acid per liter.
A basic buffer system is a solution that can maintain an acidic pH when more acid or base is added.
A basic buffer system maintains a steady basic pH regardless of how much acid or base is added.
A basic buffer system is a solution that can maintain a basic pH when more acid or base is added
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Customer: replied 4 years ago.

This is the second part of the assignment, it would not allow me to post this all at once.

Imagine yourself as the Lead Analytical Chemist at Kaplan Industries. Your first big assignment is to investigate the strength of several commercial antacids for the Food and Drug Administration (FDA). They have sent five antacids to be tested with a back-titration that works as follows:

First, each antacid tablet is mixed with 40 mL of 0.1 M HCl—this acidic solution is the same stuff that is in stomach acid, and one antacid pill is nowhere near enough to neutralize all 40 mL of the acid.

So, to see how much extra help each antacid pill needs to neutralize 40 mL of 0.1 M HCL, you add 0.05 M NaOH drop-by-drop to back-titrate the solution until the pH is neutral.

What this means is that, the stronger the antacid tablet, the less NaOH it will take to help bring the acid to neutral. (In other words, the stronger antacid tablets counteract more of the original HCl, leaving the solution closer to neutral before the NaOH is added.)

1. Which is the strongest antacid, on a single-dose basis? Which is the weakest? Explain and show your calculations.

2. Which are the strongest and weakest, on a by-weight (mass) basis?

3. When people do back titrations, they usually watch the solution for a color change when the solution becomes neutral. What might you have used in the above experiment to get this color change to happen in the solution? At what pH would the solution have been neutral?

4. If you had walked into the lab, only to discover that you only had 0.1 M sulfuric acid available to run your tests, how might this have affected your calculations? Why?

5. In most of the antacids you tested, the active ingredient is aluminum hydroxide. Here is an unbalanced reaction that shows how this chemical neutralizes HCl (the main ingredient in stomach acid). Please provide a balanced version of this equation:

Al(OH)

3 + HCI AlCl3 + H20

6. The FDA requires that all of its reports be super-brief—short enough so that they can be sent via text message to all of its lab sites across the country. As you probably know, the word limit for text messages is very small, so your goal here is to describe precisely what you did to test the antacids in

fewer than 150 words. In this brief report, you should provide the FDA with the major findings from your tests and let them know generally how you performed your tests.

 Mass of one dose antacid 20.0 g 21.0 g 18.0 g 18.3 g 17.5 g mL NaOH used in back-titration 24.1 mL 22.4 mL 20.0 mL 19.9 mL 24.4 mL
Customer: replied 4 years ago.