Chem 1010 Tutorials
Tutorial 4B – Combustion Analysis and
Balancing Chemical Equations
Fall 2013
1.
The complete combustion of 0.285 g of a pure hydrocarbon yielded 0.878 g CO 2 and 0.405 g H2O. What is
the mass % C in this hydrocarbon?
2.
A 4.05 g sample of a compound containing only C, H, and O was burned completely. The only combustion
products were 10.942 g CO2 and 4.476 g H2O. What is the empirical formula of the compound?
3.
Vitamin C (ascorbic acid) is composed of carbon, hydrogen, and oxygen. A 3.87 g sample of Vitamin C
gives 5.80 g of CO2 and 1.58 g of H2O during combustion analysis.
a)
What is the empirical formula of Vitamin C?
b)
If the molar mass of Vitamin C is 176.1256 g/mol, what is the molecular formula?
4.
Nicotine, a substance in tobacco, is composed of C, H, and N. A 7.327 mg sample of nicotine is combusted
and forms 19.876 mg of CO2 and 5.698 mg of H2O. Calculate nicotine’s empirical formula. What is its
molecular formula if its molar mass is 162.2 g/mol?
5.
Balance the following chemical equations:
a)
___C2H8(g) + ___N2O4(g)
___N2(g) + ___CO2(g) + ___H2O(l)
b)
___C6H14(g) + ___O2(g)
___CO2(g) + ___H2O(l)
c)
___H2O2(aq)
___O2(g) + ___H2O(l)
d)
___NH3(g) + ___O2(g)
___NO(g) + ___H2O(l)
e)
___H3PO4(aq) + ___NaOH(aq)
___Na3PO4(aq) + ___H2O(l)
f)
___Cl2O5(aq) + ___H2O(l)
___HClO3(aq)
g)
___V2O5(s) + ___H2(g)
___V2O3(s) + ___H2O(l)
h)
___C2H6O(l) + ___O2(g)
___CO2(g) + ___H2O(l)
ANSWERS:
1. 84.1% C
5.
2. C7H14O
3. EF = C3H4O3
MF = C6H8O6
4. EF = C5H7N
a)
___C2H8(g) + _2_N2O4(g)
_2_N2(g) + _2_CO2(g) + _4_H2O(l)
b)
_2_C6H14(g) + _13_O2(g)
_12_CO2(g) + _14_H2O(l)
c)
_2_H2O2(aq)
___O2(g) + _2_H2O(l)
d)
_4_NH3(g) + _5_O2(g)
_4_NO(g) + _6_H2O(l)
e)
___H3PO4(aq) + _3_NaOH(aq)
___Na3PO4(aq) + _3_H2O(l)
f)
___Cl2O5(aq) + ___H2O(l)
_2_HClO3(aq)
g)
___V2O5(s) + _2_H2(g)
___V2O3(s) + _2_H2O(l)
h)
___C2H6O(l) + _3_O2(g)
_2_CO2(g) + _3_H2O(l)
MF = C10H14N2