Chem 1010 Tutorials
Tutorial 7B – Solutions – Molarity,
Dilutions and Titrations
Fall 2013
Molarity
1.
What is the molarity of 40.0 g NaCl in 250.0 mL of solution?
2.
Given a 0.1000 M solution, calculate:
a) moles of solute in 10.00 L of solution;
b) milliliters of solution that contain 0.4000 mol of solute.
3.
How many grams of NaCl are needed to make 125 mL of 0.200 M NaCl solution?
4.
What is the concentration of NO3—(aq) ion in the solution formed when 10.0 g of Fe(NO3)3(s) are
dissolved in enough water to make 250.0 mL of solution? (Note: molar mass of Fe(NO 3)3 =
241.86 g mol—1)
5.
How many liters of 0.10 M Na3PO4 contain 0.27 mol of Na+?
Dilutions
6.
What is the final concentration when 75 mL of 6.0 M HCl solution is diluted to 0.15 L?
7.
How many milliliters of 16 M HNO3 solution are required to prepare 0.50 L of 0.10 M HNO3?
8.
When left in an open beaker for a period of time, the volume of 275 mL of 0.105 M NaCl is
found to decrease to 237 mL due to the evaporation of water. What is the new concentration of
the solution?
9.
A BaCl2 solution is 0.84 M. How many liters of this BaCl2 solution are needed to make 250.0 mL
of a solution that is 0.500 M in Cl— ions?
Solution Stoichiometry & Titrations
10.
Aqueous potassium hydroxide reacts with perchloric acid to form aqueous potassium
perchlorate and water. What volume of 0.0496 M HClO4 is required to react with 25.0 mL of
0.505 M KOH?
11.
What volume of 0.260 mol L—1 silver nitrate solution, AgNO3(aq) is required to react completely
with 25.00 mL of 0.315 mol L—1 sodium sulfide solution, Na2S(aq)?
Na2S(aq) + 2 AgNO3(aq) → 2 NaNO3(aq) + Ag2S(s)
12.
Consider the reaction:
2 AgNO3(aq) + K2CrO4(aq) → Ag2CrO4(s) + 2 KNO3(aq)
a) How many mL of 0.150 M AgNO3(aq) are required to react completely with 175 mL of 0.0855
M K2CrO4(aq)?
b) What mass of Ag2CrO4(s) is formed?
c) How many mL of 0.60 M AgNO3 solution must be added to excess K2CrO4(aq) solution to
produce 3.0 g of Ag2CrO4(s)?
13.
Consider the reaction:
CaCl2(aq) + Na2CO3(aq) → CaCO3(s) + 2 NaCl(aq)
When 145 mL of 0.600 M CaCl2(aq) is added to 105 mL of 0.200 M Na2CO3(aq), how many grams of
CaCO3(s) are formed?
14.
If 9.81 mL of 0.1059 M hydrochloric acid is required in the titration of 50.00 mL of aqueous
ammonia, what is the molarity of the ammonia?
15.
What volume of 0.250 mol·L—1 nitric acid is required to react with 3.70 g of calcium hydroxide,
Ca(OH)2, according to the following equation?
2 HNO3(aq) + Ca(OH)2(aq) → Ca(NO3)2(aq) + 2 H2O(l)
16.
How many milliliters of 0.100 M NaOH are needed to completely neutralize 25.0 mL of 0.250 M
H3PO4?
The reaction is:
3 NaOH(aq) + H3PO4(aq) → Na3PO4(aq) + 3 H2O(l)
17.
To make 1.00 L of 0.750 M ZnCl2(aq) from the reaction:
2 HCl(aq) + ZnO(s) → ZnCl2(aq) + H2O(l)
How much of the following reactants must be used (then diluted to 1.00 L):
i) ______ mL of 2.00 M HCl(aq)
ii) _______ g of ZnO(s) (Molar mass = 81.4084 g/mol)
18.
The titration of 10.00 mL of an H2SO4(aq) solution required 21.52 mL of 0.2000 M NaOH(aq). What
is the molarity of the H2SO4(aq) solution?
Answers:
1. 2.74 M NaOH
3
2. a) 1.000 mol of solute
b) 4.000 x 10 mL of solution
3. 1.46g NaCl
4. 0.496 M NO3
5. 0.90 L of Na3PO4
6. 3.0 M HCl
7. 3.1 mL of HNO3
8. 0.122 M NaCl
9. 0.074 L BaCl2
10. 0.255 L HClO4
11. 0.0606 L AgNO3
12. a) 0.199 L AgNO3
b) 4.96 g Ag2CrO4
c) 30 mL AgNO3
13. 2.10 g CaCO3
14. 0.0208 M NH3
15. 0.399 L HNO3
16. 188 mL NaOH
—
17. 750. mL HCl and 61.1 g ZnO
18. 0.2152 M H2SO4