11 mark
A compound has an empirical formula of C2H6O and a molar mass of 92.16.
What is the molecular formula of this compound?
C2H6O
C4H12O2
C6H18O3
C8H24O4
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Syllabus Edition
First teaching 2023
First exams 2025
|
Counting Particles by Mass: The Mole (HL IB Chemistry)
Exam Questions
2 hours29 questions
21 mark
Ethane has the formula C2H6. What is the mass in grams of one molecule of ethane?
(RAMs: C = 12.0; H = 1.0)
1.8 x 1025
3.0 x 10-23
30.0
5.0 x 10-23
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31 mark
Shown below are four molecular formulas. Which one is also an empirical formula?
PCl5
CH3COOH
H2O2
C6H12O6
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41 mark
The relative atomic mass is a way of representing the mass of an atom.
Which of the following definitions is correct for the term relative atomic mass?
the mass of an electron
1/12 the mass of a carbon-12 atom
the mass of a hydrogen-1 atom
the mass of a proton
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51 mark
Which of the following shows the relative formula mass of ammonium sulfate, (NH4)2SO4?
70.00
132.00
114.09
132.17
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61 mark
Which amount of the following substances contains the smallest quantity of ions?
2 mol of KOH
1 mol of NH4Br
2 mol of MgCl2
1 mol of Fe2O3
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71 mark
A sample of hydrated calcium sulfate, CaSO4∙
H2O, has a relative formula mass of 172.19
What is the value of ?
1
2
3
4
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11 mark
A compound of molar mass 92 g mol-1 contains 12 g of carbon, 2 g of hydrogen and 32 g of oxygen. What is the molecular formula of the compound?
CH2O2
CH2O
C2H4O2
C2H4O4
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21 mark
Ethanoic acid has the formula CH3COOH. How many carbon atoms are present in
0.1 mol of ethanoic acid?
6.0 x 1022
1.2 x 1023
6.0 x 1023
1.2 x 1024
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31 mark
A compound contains carbon and hydrogen only. The amount of carbon is 80% by mass. What is the empirical formula of the compound?
(RAMs, H = 1.01, C = 12.01)
CH
CH2
CH3
CH4
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41 mark
A hydrated carbonate of an unknown Group 1 metal has the formula X2CO3∙10H2O and is found to have a relative formula mass of 286.19
What is the Group 1 metal?
Rb
K
Na
Li
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51 mark
The diagram below shows the skeletal formula of phenazine.
What is the empirical formula of phenazine?
C6H6N
C12H8N2
C6H4N
C12H12N2
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61 mark
A coin contains 5.869% nickel by mass. If the coin weighs 10.00g, how many nickel atoms are in the coin?
4.30 x 1022
3.01 x 1023
6.02 x 1025
6.02 x 1021
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11 mark
10 cm3 of methane and 10 cm3 of ethane were sparked with an excess of oxygen. Once cooled, the remaining gas was passed through aqueous potassium hydroxide, which absorbs carbon dioxide.
Assume all measurements were taken at 25˚C and 1 atm pressure.
What volume of gas is absorbed by the alkali?
45 cm3
30 cm3
20 cm3
10 cm3
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21 mark
Which sample contains the largest amount, in mol, of atoms?
0.30 mol of P2O5
0.40 mol of CuSO4.5H2O
0.50 mol of CH3COOH
0.90 mol of H2O
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31 mark
How many ions are present in 0.02 mol of (NH4)3PO4?
8.0 x 10-2
1.2 x 1022
4.8 x 1022
2.4 x 1023
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