### chemical equations, oxidation/redox reactions, nuclear, etc, science homework help

1. Which of the following will NOT form a precipitate?

a) Zn(NO3)2 and Na2S (aq)

b) Rb2S(aq) and LiCl (aq)

c) K2CO3(aq) and Mg(NO3)2 (aq)

d) Na3PO4 (aq) and AgNO3(aq)

2. A strong monoprotic acid ionizes in water. If the [H3O+] concentration is 1.56 x 10^-4 M, what else is true?

a) pH=10.19

b) The solution contains more hydronium ions than hydroxide ions

c) pOH= 1.56 x 10-4 M

d) The solution contains equal concentrations of hydroxide and hydronium ions.

3. When a mole of lithium reacts chemically with hydrogen to form lithium hydride, the energy released is found to be roughly 90 joules. How much mass is lost?

a) 1.0 x 10^-15 kg

b) 2.7 x 10^10 kg

c) 1.0 x 10^15 kg

d) 3.0 x 10 ^-7 kg

4. Which of the following represents beta emission?

a) 30/15 P —> 30/14 Si +_____

b) 238/92 U —-> 234/90 Th +______

c) 14/7 N + 4/2 He —-> 17/8 O + _____

d) 234/90 Th —–> 234/91 Pa + ______

5. Which equivalence factor should you use to convert from 38.2 grams of K to moles of K ?

a) (38.2 g k / 39.10 g k )

b) (38.2 g k /1 mol k)

c) (1mol k / 38.2 g k )

d) (1 mol k /39.10 g k)

6. Given the following chemical equation, if 50.1 grams of silicon dioxide is heated with excess carbon and 32.3 grams of silicon carbide is produced, what is the percent yield for this reaction? SiO2 (s) + 3 C (s) —> SiC (s) + 2CO (g)

a) 97%

b) 75%

C) 103%

d) 48%

7. The equation, E=mc2, shows that mass and energy are different forms of the same thing and can be interconverted.

True or False

8. Consider the following unbalanced redox reaction: MnO4- (aq) + SbH3 (aq) —> MnO2 (s) + Sb(s) What is being reduced?

a) MnO4

b) SbH3

c) MnO2

d) Sb

9. Ethylene Glycol, C2H602, is a non-volatile substance unable to form ions in water. If 38.6 grams of ethylene glycol is dissolved in 175 grams of water, what is the freezing point of the solution? Kf = 1.86 C/m; Kb= 0.512 C/m

a) -6.61 C

b) 1.82 C

c) 6.61 C

d) -1.82 C

10. Which of the following represents gamma emission?

a) 30/15 P —> 30/14 Si + _____

b) 238/92 U —-> 234/90 Th + ______

c) 14/7 N = 4/2 He —> 17/8 O + _____

d) 131/53 I —> 131/53 I + _____

11. Given the following chemical equation, how many grams of hydrogen are necessary to react with 2.85 moles of carbon monoxide? CO (g) + 2H2 (g) —-> CH3OH (g)

a) 11.5 g

b) 5.76 g

c) 2.88 g

d) 4.04 g

12. Sodium carbonate solution reacts with stronium chloride solution. Predict whether the reaction will produce a precipitate.

b) No. all products are soluble because they each contain metal and no-metal components.

c) Yes. stronium carbonate will precipitate because each ion is a polyvalent.

d) Yes. both sodium chloride and strontium carbonate will precipitate because they both contain metals

13. A solution of Mg(OH)2 has a hydroxide concentration of 6.04 x 10 -2 M. What is the pOH of this solution?

a) pOH = 1.22

b) pOH = 12.78

c) pOH = 1.52

d) pOH= 12.48

14. A cylinder with a movable piston contains a fixed amount of gas at a constant pressure. Initially, the cylinder contains 0.25 liters of air at 0 (zero) degrees C. When the temperature is increased to 35 degrees C, the air will occupy what volume?

a) 0.28 L

b) 0.88 L

c) 8.75 L

d) 35.25 L

15. You are given 175 grams of a substance with a half-life of 0.25 years. How much time has passed if you now have 21.88 grams?

a) 0.75 yrs

b) 3 yrs

c) 3.75 yrs

d) 0.25 yrs

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