--Partial Credit Question Exam 3 CHEM 1310 WS12 NAME:_______________

NOTE: to receive ANY credit, work must be shown for each problem .

Cesium metal was added to water. A reaction took place, the cesium metal was consumed and hydrogen

gas was released.

Part 1) (5 points) Write a balanced chemical equation and indicate the states of matter for the reaction.

~ l (,S oN ~\;tt) Or ~

T'-i Cs D \1} ~ A-J... 5CoJ..J ht (W1JJ f c.o/rc:...-cA

Part 2) (10 points) Write both half reactions and indicate which material was oxidized and which

material was reduced .

c . J.Ji V"'-'L c.Sl"~ L G~ I +

L:J /) .­

L (...G., ov} tu..-tv-v I c.r.1

Go ((... t.. +

Part 3) (5 points) Which materials were 1) the reducing agent and 2) the oxidizing agent for the above

reaction ?

I~ r (.,. \JC \ IV.j C "'t l~ lOt. i\\1

~

EXAM 3 WS12 CHEM 1310 Green NAME, _ _ _______

MULTIPLE CHOICE Choose the one alternative that best completes the statement or answers the

question.

1) Under appropriate conditions, nitrogen and hydrogen undergo a combination reaction to yield

ammonia :

N2(g) + 3 H2(g) ~ 2 N H3(g)

A 9.3-g sample of hydrogen requires __g of N2 for a cQ~te reaction .

A) 3.9 x 102 B) 2.0 C} 1.3 X 102 0) 43 E) 4.6

2) Which of the following is soluble in water at 25°C?

A) Fe(OHh B) FeS C) FeC03 0) Fe(N03)

B) 3.52 C) 1.85 X 10-3 0) 0.104 E) 0.0657

4) Lead carbonate decomposes to give lead oxide and carbon dioxide:

PbC03(s) ~ PbO (s) + CO 2 (g)

How many grams of lead oxide will be produced by the decomposition qf 2.Ji,Q ~of lead carbonate?

A) 2.50 B) 2.61 C) 0.00936 0) 0.41 E) 2.09

5) Calcium oxide reacts w ith water in a combination reaction to produce calcium hydroxide:

CaO (s) + H20 (I) ~ Ca(OHh (s)

In a particular experiment, a 5.00-g sample of CaO is reacted with excess water and 6_11 g of Ca(OH)2 is

recovered . What is the percent yield in this experiment?

A) 122 B) 81.9 C) 7.19 0) 1.12 E) 92.4

6) The compound HCI04 is a _ '

A) strong base

B) strong acid

C) weak base

0) weak acid

E) binary compound

7) Oxidation is the and reduction is the-,

A) loss of oxygen, gain of electrons

B) gain of electrons, loss of electrons

C) gain of oxygen, loss of electrons

O~ain of oxygen, loss of mass

E) I~s of electrons, gain of electrons

--

8) A compound that is composed of only carbon and hydrogen contains 85.7% C and 14.3% H by mass.

What is the empirical formula of the compound?

A) C2H4 B) C86 H14 C) CH 2 0) CH4

9) Automotive air bags inflate when sodium azide decomposes explosively to its constituent elements:

2 NaN3(s) -7 2 Na (s) + 3 N2 (g)

How many grams of sodium azide are requ ired f o proti~18.0 g of nitrogen?

A) 41.8 B) 0.964 C) 62.7 D) 27 .9 E) 0.428

10) When aqueous solutions of AgN03 and Nal are mixed, Agi precipitates. The balanced net ionic

equation is

A) AgN03(aq) + Nal (aq) -7 Agi (s) + NaN03(aq)

B) Ag+ (aq) + N03-(aq) -7 AgN03(aq)

C) Ag+ (aq) + N03'(aq)-7 AgN03(s)

D) AgN03 (aq) + Nal (aq) -7 Agi (aq) + NaN03(s)

r~+ (aq) + r(aq) -7 Agi (s)

11) What is the concentration (M) of CH30H in a solution prepared by dissolving 11.7 g of CH30H in

sufficient water to give 230 mL of solution?

A) 1.59 x 10-3 B) 11.9 X 10-3 C) 1.59 D) 11.9 E) 0.0841

12) Which compound has the atom wit h the highest oxidation number?

A) AI(N0 2h B) Na3N C) MgS03 D) CaS E) NH 4CI

13) What are the spectator ions in the reaction between KOH (aq) and HN03 (aq)?

A) H+ and N03- B) K+ and H+ C) H+ and OH- D)OH-only E) K+ and N03­

14) A compound contains 38.7% K, 13.9% N, and 47.4% 0 by mass. What is the empirical formula ofthe

compound?

A) KN02

15) In which reaction does the oxidation number of hydrogen change?

A) SOAg) + H20 (I) -7 H2S03(aq)

B) HCI (aq) + NaOH (aq) -7 NaCI (aq) + H20 (I)

C) '4 Na (s) + 2 H20 (I) -7 2 NaOH (aq) + I-h (g)

D) 2 HCI04 (aq) + CaC03(s)-7 Ca(C104 h (aq) + H20 (I) + CO2(g)

E) CaO (s) + H20 (I) -7 Ca(OHh (s)

16) What is the concentration (M) of NaCI in a solution made by mixing 25.0 mL of 0.100 M NaCI with

50.0 mL of 0.100 M NaCI?

A) 0.0500 B) 0.0333 C) 0.0250 0) 125 E) 0.100

17) Which of the following are strong electrolytes?

1) HCI

2) CH3COOH

3) NH3

4) KCI

A) 1,2,3,4 B)1,2,4 C) 1,4 0) 2,4 E) 1,3,4

18) What are the respective concentrations (M) of Na+ and SO/ 'afforded by dissolving 0.500 moles

~04 in water and diluting to 1.33 L?

A) 0#752 and 0.376

B) 0.665 and 1.33

C) 0.665 and 0.665

0) 0.376 and 0.752

E) 1.33 and 0.665