Target: 10 Questions in 10 minutes

An IB Chemistry data booklet is helpful

1. How many molecules are in 227cm3 of ammonia gas, NH3, at stp?

  • A.   2.41 x 1022
  • B.   2.41 x 1025
  • C.   6.02 x 1021
  • D.   6.02 x 1024

2.Three identical containers are filled with gases under the same conditions as shown in the diagram below:

3 conical flasks containing different gases

Which statement is true?

  
  • A. All three containers contain the same number of atoms
  • B. Container X contains the most hydrogen atoms
  • C. Container Z contains the most molecules
  • D. Container Y has the largest mass

3. How many atoms are there in 45.4dm3 of nitrogen dioxide gas, NO2, at stp?

  • A.   1.20 x 1024
  • B.   1.81 x 1024
  • C.   2.41 x 1024
  • D.   3.61 x 1024

4. 100cm3 of butane was burned completely in oxygen. What volume of oxygen was used and what volume of carbon dioxide was formed?

 2 C4H10(g)  +  13 O2(g)  → 8 CO2(g)  +  10 H2O(l)

  
  Volume of oxygen (cm3) Volume of carbon dioxide (cm3)
A 1300 800
B 1300 400
C 650 800
D 650 400
5. 0.56g of a gaseous compound occupied 454cm3 at stp. What is the molar mass of the gas?
  • A.   14g mol-1
  • B.   28g mol-1
  • C.   56g mol-1
  • D.   112g mol-1
6. 200cm3 of methane was reacted with 600cm3 of oxygen. What is the total volume of all gases at the end of the reaction?

CH4(g)  +  2 O2(g)  → CO2(g)  +  2 H2O(l)

  • A.   200cm3
  • B.   400cm3
  • C.   600cm3
  • D.   800cm3
7. Which of the following contains the greatest number of atoms? All gas volumes measured at stp.
  • A.   454cm3 of carbon dioxide, CO2
  • B.   908cm3 of helium, He
  • C.   0.16g of methane, CH4
  • D.   0.64g of sulfur dioxide, SO2
8. 40 dm3 of hydrogen sulphide was burned in 100 dm3 of oxygen as shown:

2 H2S(g)  +  3 O2(g)  → 2 H2O(g)  +  2 SO2(g)

What volume of gaseous product formed and what volume of oxygen remained?

  
  Volume of products (dm3) Volume of oxygen (dm3)
A 40 40
B 40 60
C 80 40
D 80 60
9. 20cm3 of a hydrocarbon CxHy produced 120cm3 of carbon dioxide and 120cm3 of water vapour when burned completely in excess oxygen. What is the formula of the hydrocarbon?

All gas volumes were measure under the same conditions of temperature and pressure.

  • A.   C6H6
  • B.   C6H12
  • C.   C12H12
  • D.   C12H24
10. What volume of oxygen gas will be formed at stp when
2.40 x 1022
electrons flow in the circuit during the electrolysis of dilute sulfuric acid?

2 H2O  → O2  +  4 H+  +  4 e-

 water electrolysis
  • A.   227 cm3
  • B.   908 cm3
  • C.   2270 cm3
  • D.   22700 cm3