chapter 4 aqueous reactions and solution stoichiometry

Question 1

Which of the following is/are strong electrolytes?
I. HBr
II. CsOH
III. HF
IV. NH3
(Strong electrolytes are soluable ionic compounds, strong acids, and strong bases like group 1 metal hydroxides)

Answer 1

I and II
HF is a weak acid and NH3 is a weak base

Question 2

Which of the following best describes what type of reaction is shown below?
Na2CO3 (aq) + Ba(NO3)2 (aq) = BaCO3 (s) + 2NaNO3 (aq)
a. single replacement
b. double replacement
c. combustion
d. decomposition
e. combination

Answer 2

b. double replacement

Question 3

Which type of reaction is the following?
Mn(NO3)2 (aq) + 2NaOH (aq) = Mn(OH)2 (s) + 2NaNO3 (aq)
a. oxidation-reduction
b. single replacement
c. combustion
d. combination
e. metathesis

Answer 3

e. metathesis
(it’s just another name for double replacement)

Question 4

Predict the products and properly balance the following reaction…
KOH (aq) + H2SO4 (aq) =
hint: it’s an acid/base neutralization reaction
hint: the charge of SO4 is 2-

Answer 4

2KOH + H2SO4 = 2H2O + K2SO4

Question 5

What is the sum of the coefficients when the following equation is properly balanced?
CsOH (aq) + H2SO4 (aq) =
hint: it’s another acid/base neutralization reaction
hint: the charge of SO4 is 2-

Answer 5

6 is the sum of coefficients

The reaction should look like…
2CsOH + H2SO4 = 2H2O + Cs2SO4

Question 6

What are the spectator ions in the following reaction?
MgCl2 (aq) + 2NaOH (aq) = 2NaCl (aq) + Mg(OH)2 (s)
hint: spectator ions are part of strong electrolytes on both sides of the reaction

Answer 6

Na+ and Cl-
Because Mg(OH)2 is not a strong electrolyte probably because Mg is a group II and not a group I metal

Question 7

For the following reaction, what is the net ionic equation?
HNO3 (aq) + KOH (aq) = H2O (l) + KNO3 (aq)
hint: it’s the equation without the spectator ions

Answer 7

H + OH = H2O

KNO3 is a soluable ionic compound making it a strong electrolyte

Question 8

For the following reaction, what is the net ionic equation?
Ba(NO3)2 + 2RbF = 2RbNO3 + BaF2

Answer 8

Ba + 2F = BaF2

This one isn’t as obvious as some of the others. Ba(NO3)2 is a pretty obvious strong, soluable compound. And apparently RbF and RbNO3 are also.
BaF2 is the weak one so those elements are the ones that will stay.

Question 9

Which of the following will affect the solubility of O2 (g) in H2O?
I. A change in temperature
II. A change in pressure
III. A change in the surface area of the liquid
(multiple answers are acceptable)

Answer 9

I and II

Question 10

What is the oxidation state of carbon in diamond?
(see study guide. oxidation states have their own set of rules)
-4? -2? 0? +2? +4?

Answer 10

Carbon is just carbon. It’s in its elemental form albeit diamond is just one type of alloptrope of carbon.
So… The oxidation state is zero

Question 11

What is the oxidation state of oxygen in K2O2?
-4? -2? -1? 0? +2?

Answer 11

-1
Ions in ionic compounds get their typical charge (and it’s just asking for the charge of oxygen not O2)

Question 12

What is the oxidation state of bromine in KBr?
-1? +1? +3? +5? +7?

Answer 12

-1
Ions in ionic compounds get their typical charge

Question 13

What is the oxidation state of sulfur in K2SO3?
-2? 0? +2? +4? +6?

Answer 13

+4
Oxygen is part of a polyatomic ion so its charge is -2 times 3 oxygens. K just gets its normal charge times 2 K is -2
You can set up an equation like
2 + x -6 = 0
Sulfur is your x. Solve for x.

Question 14

What is the oxidation state of Al in Al(NO3)3?
0? +1? +2? +3? +4?

Answer 14

+3
This one is kind of hard because you don’t go with the polyatomic ion rule. Instead, you use the ionic compound rule.
NO3 has a 1- charge so Al has to make up for that x3

Question 15

What is the oxidation state of carbon in H2CO3?
0? +1? +2? +3? +4?

Answer 15

+4
Again, this one is a little weird. You use the rule that oxygen is 2- because it’s in a polyatomic ion and hydrogen is +1 because it’s bonded to non-metals.

Question 16

What is the oxidation state of phosphorus in H3PO4?
-5? -3? +1? +3? +5?

Answer 16

+5

Question 17

What is the oxidation state of carbon in C2H4O?
-4? -1? 0? +1? +4?

Answer 17

-1
Follow the rules of molecular compounds

Question 18

What is the oxidation state of chromium CrO4 2-
-4? -2? +2? +4? +6?

Answer 18

+6
You follow the polyatomic ion rules. The trick is that, instead of equaling zero, this starts out with a -2 charge.

Question 19

Which type of reaction is the following?
2Al + 6 HCl = 2AlCl3 + 3H2?
a. precipitation
b. single replacement
c. combustion
d. combination
e. metathesis

Answer 19

b. single replacement

Question 20

Which of the following best describes what type of reaction is shown below?
Zn + 2AgNO3 = Zn(NO3)2 + 2Ag
a. single replacement
b. double replacement
c. combustion
d. decomposition
e. combination

Answer 20

a. single replacement

Question 21

Based upon the activity series, which of the following reactions is spontaneous? You can choose more than one.
I. 2AgNO3 + Cu = Cu(NO3)2 + 2Ag
II. NaNO3 + K = KNO3 + Na
III. FeCl2 + H2 = Fe + 2HCl
(see study guide for activity series table)

Answer 21

I. and II.

Question 22

If 10.6 grams of Na2CO3 is dissolved to a total volume of 50 ml, what is the molar concentration of Na2CO3 in the resulting solution?
hint: M = moles of solute / liters of solution
a. 0.05 M
b. 0.2 M
c. 0.5 M
d. 2 M
e. 4 M

Answer 22

2 M
convert to moles
convert to liters

Question 23

To what volume must 117 grams NaCl be dissolved to produce a 0.4 M solution?
hint: M = n / V L
a. 5 ml
b. 500 ml
c. 1 L
d. 2 L
e. 5 L

Answer 23

5 L
convert to moles
set up the equation

Question 24

What mass of LiNO3 must be dissolved to a final volume of 200 ml to produce a 0.5 M solution?
hint: M = n / V L
a. 6.9 grams
b. 13 grams
c. 27.4 grams
d. 53 grams
e. 138 grams

Answer 24

6.9 grams
convert your final answer from moles to grams

Question 25

If 250 ml of 0.08 M NaOH is diluted to a final volume of 1 L, what is the resulting concentration of the solution? hint: (M1)(VL1) = (M2)(VL2) a. 0.005 M b. 0.02 M c. 0.04 M d. 0.32 M e. 3.2 M

Answer 25

0.02 M

Question 26

Approximately how much water must be added to 40 ml of 3 M HCl to produce a solution with a final concentration of 0.15 M? hint: (M1)(VL1) = (M2)(VL2) a. 40 ml b. 80 ml c. 400 ml d. 760 ml e. 1600 ml

Answer 26

760 ml You have to convert from ml to L back to ml's And then subtract your original volume from your final volume because it's asking how much water 'must be added'

Question 27

To what final volume must 150 ml of 0.6 M (molar) KBr be diluted to produce a 0.1 M solution? hint: (M1)(V1) = (M2)(V2) a. 300 ml b. 450ml c. 600 ml d. 900 ml e. 1200 ml

Answer 27

900 ml

Question 28

What volume of 0.2 M KOH is required to neutralize 100 ml of 0.8 M HCL? a. 20 ml b. 50 ml c. 100 ml d. 400 ml e. 800 ml

Answer 28

So basically, if you write out the acid/base neutralization reaction and then balance, you'll, see that it doesn't require much balancing and that everything reacts in a 1:1 mole ratio. And if that's the case, you can do (M KOH)(V KOH) = (M HCl)(V HCl)

Question 29

If 108 grams of Al react completely with 2.5 L of 2M (molar) HCl, what is the theortetical yield of H2? 2 Al + 6 HCl = 2AlCl3 + 3H2 a. 5 grams b. 12 grams c. 50 grams d. 78 grams e. 162 grams

Answer 29

5 grams There's a lot going on here. You need to get both compounds into moles by doing 2 different types of conversions. Then I saw that HCl was the limiting reagent. I calculated the percentage of H2 yielded based on the 5 moles of HCl. Finally, you need to convert your answer back into grams.

Question 30

What volume of 0.01 M Ba(NO3)2 is required to completely react with 500 ml 0.004 M RbF in the following reaction? Ba(NO3)2 + 2RbF = 2RbNO3 + BaF2 a. 10 ml b. 100 ml c. 1000ml d. 10 L e. 100 L

Answer 30

100 ml This one takes a little thinking. This is a 1:2 mole ratio so basically, at the very end, I just divided my answer by 2. (500)(.004) = (.01)(x) And then divide by 2

Question 31

What volume of 1.0 M AgNO3 must be added for 6.36 grams of copper to react completely in the following reaction? 2AgNO3 + Cu = Cu(NO3)2 + 2Ag a. 20 ml b. 50 ml c. 200 ml d. 2 L e. 20 L

Answer 31

200 ml This one isn't bad. See how many moles of Cu 6.36 grams equals. You know that you will need twice as much AgNO3. It gives you the molarity of AgNO3 so you just need to use the equation M = n/VL Then convert to ml's

Question 32

If 100 ml of 0.4 M MgCl2 reacts completely with 500 ml 0.1 M NaOH, what is the theoretical yield of Mg(OH)2? MgCl2 + 2NaOH = 2NaCl + Mg(OH)2 a. 1.5 grams b. 15 grams c. 29 grams d. 58 grams e. 126 grams

Answer 32

1.5 grams I actually got 1.45 grams This one threw me a bit. First, I used M = n/VL to figure out the moles of each reactant. The limiting reactant is the NaOH so that's what you want to work with. .05 moles of NaOH is 2.5% of the 2 moles of NaOH in the given equation. So what's 2.5% of Mg(OH)2? It's just some percentage math which means, don't mess of the decimal places. Covert back into grams and you should have your answer.