Title: Matter and Measurement
1CHAPTER 4 Chemical Equations and Stoichiometry
Chapter 4 Quiz points - complete all assigned
homework problems from the chapter - submit on
Monday, Feb 12 - problems selected randomly for
grading
2Road Map
- Where we were
- Balanced equations from neutral formulas,
containing ionic equations, and one with
polyatomic ions (Table 3.1 available on test) - Relationships when comparing different
compounds, must always go through a MOLE
comparison - Limiting reactant (reagent)
- Where we are going
- Percent yield
- Chemical equations and chemical analysis
3Practice Problem 4-1
- When aqueous silver nitrate and sodium chromate
solutions are mixed, a reaction occurs that forms
solid silver chromate and a solution of sodium
nitrate. If 257.8 mL of a 0.0468 M solution of
silver nitrate is added to 156.00 ml of a 0.095 M
solution of sodium chromate, what mass of solid
silver chromate (M 331.8 g/mol) will be formed? - 2 AgNO3(aq) Na2CrO4(aq) ? Ag2CrO4(s) 2
NaNO3(aq)
4Practice Problem 4-1 Answer
5Practice Problem 4-2
- A) If 257.8 mL of a 0.0468 M solution of lead(II)
nitrate is added to 156.00 mL of a 0.095 M
solution of sodium sulfide, what mass of solid
lead(II) sulfide will be formed? - Pb(NO3)2(aq) Na2S(aq) ?
- PbS(s) 2 NaNO3(aq)
6Practice Problem 4-2 Answer
- A) 2.89 g PbS
- (theoretical)
- B) Actually make 2.64g (actual)
- What is your percent yield?
7Practice Problem 4-2B Answer
- B) Actually make 2.64g
- What is your percent yield?
- yield 100
- yield 100
- .9135 x 100 91.349
8Practice Problem 4-3
- Potassium permanganate reacts with oxalic acid in
aqueous sulfuric acid according to the following
equation - 2 KMnO4 5 H2C2O4 3 H2SO4 ?
- 2 MnSO4 10 CO2 8 H2O K2SO4
- If you start with 3.225 g of H2C2O4 and 75.0 mL
of 0.250 M of KMnO4 and the percent yield is 85.3
, what is the actual yield of CO2?
9Practice Problem 4-3 Answers
10Practice Problem 4-4
- Given the chemical reaction between iron and
water to form the iron oxide, Fe3O4 and hydrogen
gas given below. If 4.55 g of iron is reacted
with sufficient water to react all of the iron to
form rust, what is the percent yield if only 6.02
g of the oxide are formed? - 3 Fe(s) 4 H2O(l) ? Fe3O4(s) 4 H2(g)
11Practice Problem 4-4 Answer
12Practice Problem 4-5
- Ammonia is produced by the Haber process using
nitrogen and hydrogen gas. If 85.90 g of
nitrogen are reacted with 21.66 g hydrogen and
the reaction yielded 98.67 g of ammonia. What
was the percent yield of the reaction? - N2(g) 3 H2(g) ? 2 NH3(g)
13Practice Problem 4-5 Answer
14Chemical Analysis
- 72. What mass of lime, CaO, can be obtained by
heating 125 kg of limestone that is 95 by mass
CaCO3? - CaCO3 (s) ? CaO (s) CO2 (g)
- 6.65 X 104 g CaO
15Chemical Equation
- A dry-cleaning solvent (M 146.99 g/mol) that
contains C, H, and Cl is suspected to be a
cancer-causing agent. When a 0.250 g sample was
studied by combustion analysis, 0.451 g of CO2
and 0.0617 g of H2O formed. Calculate the
molecular formula. - Empirical C3H2Cl
- Molecular C6H4Cl2
16Are you up to the challenge?
- Iodine is made by the reaction
- 2 NaIO3 (aq) 5 NaHSO3 (aq) ?
- 3 NaHSO4 (aq) 2 Na2SO4 (aq) H2O (l) I2
- Name the two reactants
- If you wish to prepare 1.00 kg of I2, what mass
of NaIO3 is required? - What mass of NaHSO3?
17p.162b
18Next Lesson
19Balancing Equations
- ____C3H8(g) _____ O2(g)
----gt _____CO2(g) _____ H2O(g)
____B4H10(g) _____ O2(g)
----gt ___ B2O3(g) _____ H2O(g)
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