Equation Stoichiometry 2.notebook
November 19, 2013
Equation Stoichiometry
Worksheet­2
1.
Exactly 120.0 g of propane gas, C3H8, undergoes combustion in excess oxygen. a)
Write a BME for this reaction:
C3H8(g) + 5O2(g) à 3CO2(g) + 4H2O(g)
b)
Calculate the masses of products formed:
120.0 g C3H8 x (1 mol C3H8/44.0 g C3H8) x (3 mol CO2/1 mol C3H8) x (44.0 g CO2/1 mol CO2) = 360. g CO2
120.0 g C3H8 x (1 mol C3H8/44.0 g C3H8) x (4 mol H2O/1 mol C3H8) x (18.0 g H2O/1 mol H2O) = 196 g H2O
c)
Calculate the mass of oxygen gas needed to react with the 120.0 g of propane:
120.0 g C3H8 x (1 mol C3H8/44.0 g C3H8) x (5 mol O2/1 mol C3H8) x (32 g O2/1 mol O2) = 436 g O2
or
120.0 g + X = 360. g + 196 g; X = 436 g O2
Nov 17­5:38 PM
2.
A 2.000 gram sample of sodium reacts with pure chlorine gas. a)
Write a BME for this reaction:
2 Na(s) + Cl2(g) à 2NaCl(s)
b)
Calculate the mass of chlorine gas required to react with the sodium:
2.00 g Na x (1 mol Na/23.0 g Na) x (1 mol Cl2/2 mol Na) X (71.0 g Cl2/1 mol Cl2) = 3.09 g Cl2
c)
Determine the mass of product formed.
2.00 g Na x (1 mol Na/23.0 g Na) x (2 mol NaCl/2 mol Na) x (58.5 g NaCl/1 mol NaCl) = 5.09 g NaCl
or
2.00 g Na + 3.09 g Cl2 = Xg NaCl, X = 5.09 g NaCl
Nov 17­5:39 PM
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Equation Stoichiometry 2.notebook
3.
November 19, 2013
Calculate the masses of hydrogen and nitrogen gases needed to react to produce exactly 1.00 kilograms of ammonia, NH3. Include a BME for the reaction.
3H2(g) + N2(g) à 2NH3(g)
1.00 X 103 g NH3 x (1 mol NH3/17.0 g NH3) x (3 mol H2/2 mol NH3) x (2.0 g H2/1 mol H2) = 176 g H2
Therefore, 176 g H2 + X g N2 = 1000 g NH3; X = 824 g N2
or
1.00 X 103 g NH3 x (1 mol NH3/17.0 g NH3) x (1 mol N2/2 mol NH3) x (28.0 g N2/1 mol N2) = 824 g N2
Nov 17­5:40 PM
4.
Sulfur dioxide gas undergoes combustion to yield sulfur trioxide gas. If 250.0 g of sulfur dioxide gas reacts with excess oxygen gas, determine the mass of sulfur trioxide gas produced.
a)
Write a BME for this reaction:
2SO2(g) + O2(g) à 2SO3(g)
b)
If 250.0 g of sulfur dioxide reacts with excess oxygen gas at STP, determine the mass of sulfur trioxide produced:
250.0 g SO2 x (1 mol SO2/64.1 g SO2) x (2 mol SO3/2 mol SO2) x (80.1 g SO3/1 mol SO3) = 312.4 g SO3
c)
Determine the volume of oxygen gas needed to completely react with the 250.0 g of sulfur dioxide:
250.0 g SO2 x (1 mol SO2/64.1 g SO2) x (1 mol O2/2 mol SO2) x (22.4 L/1 mol) = 43.68 L O2
Nov 17­5:40 PM
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Equation Stoichiometry 2.notebook
5.
November 19, 2013
A 2.50 g sample of mercury(II)oxide is heated until it completely decomposes to its elements.
a)
Write a BME for this reaction:
2HgO(s) à 2Hg(l) + O2(g)
b)
Calculate the masses of products formed:
2.50 g HgO x (1 mol HgO/216.6 g HgO) x (2 mol Hg/2 mol HgO0 x (200.6 g Hg/1 mol Hg) = 2.32 g Hg
therefore, 2.50 g HgO = 2.32 g Hg + X g O2; X = 0.18 g O2
Or, 2.50 g HgO x (1mol HgO/216.6 g HgO) x (1 mol O2/2 mol HgO0 x (32.0 g O2/1 mol O2) = 0.18 g O2
c)
If the density of mercury is 13.6 g/mL, calculate volume of liquid mercury will be produced?
2.32 g Hg x (1.00 mL/13.6 g) = 0.17 mL
d)
Calculate the volume the oxygen gas would occupy at STP:
0.18 g O2 x (1 mol O2/32.0 g O2) x (22.4 L O2/1 molO2) = 0.126 L O2
Nov 17­5:41 PM
6.
A sample of sodium chlorate is heated until it completely decomposes.
a)
Write a BME for this decomposition reaction:
2NaClO3(s) à 2NaCl(s) + 3O2(g)
b)
Calculate the mass of sodium chlorate that must be decomposed to produce 200.0 mL of the gas at STP:
200.0 mL O2 x (1 L/1000 ml) x (1 mol O2/22.4 L O2) x (2 mol NaClO3/3 mol O2) x (106.5 g NaClO3/1 mol NaClO3) = 0.634 g NaClO3
c)
If 0.500 g of the sodium chlorate is decomposed, determine the mass of solid product made:
0.500 g NaClO3 x (1 mol NaClO3/106.5 g NaClO3) x (2 mol NaCl/2 mol NaClO3) x (58.5 g NaCl/1 mol NaCl) = 0.275 g NaCl
d)
Will the solid produced in (c) conduct an electric current? Explain.
No because in solid phase ions are held in fixed lattice positions and are note free to move
Nov 17­5:42 PM
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