Find empirical and molecular formulae
12th grade (Year 13 in England) · 11 questions · Common Core: NGSS.HS-PS1-7 · England: GCSE Chemistry: Quantitative chemistry, A level Chemistry: Amount of substance
Name
Date
Score/ 11
Question 1
A compound has the empirical formula NO₂ (mass of one unit = 46) and Mr = 92. How many empirical units are in one molecule?
Answer
Question 2
Find the empirical formula: a compound is 40 % carbon, 6.7 % hydrogen and 53.3 % oxygen (Ar: C = 12, H = 1, O = 16).
- A. CHO
- B. C₂H₄O
- C. CH₂O
- D. C₆H₁₂O₆
Question 3
A compound has the empirical formula CH₂O (mass of one unit = 30) and Mr = 60. How many empirical units are in one molecule?
Answer
Question 4
Find the empirical formula: a compound is 30.4 % nitrogen and 69.6 % oxygen (Ar: N = 14, O = 16).
- A. N₂O₄
- B. NO
- C. NO₂
- D. N₂O
Question 5
A compound has the empirical formula NO₂ (mass of one unit = 46) and Mr = 92. How many empirical units are in one molecule?
Answer
Question 6
Find the empirical formula: a hydrocarbon is 80 % carbon and 20 % hydrogen by mass (Ar: C = 12, H = 1).
- A. C₂H₆
- B. C₄H
- C. CH₃
- D. CH₄
Question 7
A compound has the empirical formula CH₂ (mass of one unit = 14) and Mr = 56. How many empirical units are in one molecule?
Answer
Question 8
Find the empirical formula: 11.2 g of iron combines with 4.8 g of oxygen (Ar: Fe = 56, O = 16).
- A. Fe₃O₄
- B. Fe₂O₃
- C. FeO
- D. FeO₃
Question 9
A compound has the empirical formula C₂H₅ (mass of one unit = 29) and Mr = 58. How many empirical units are in one molecule?
Answer
Question 10
Find the empirical formula: a hydrocarbon is 80 % carbon and 20 % hydrogen by mass (Ar: C = 12, H = 1).
- A. CH₄
- B. C₄H
- C. C₂H₆
- D. CH₃
Question 11
A compound has the empirical formula CH₂O (mass of one unit = 30) and Mr = 60. How many empirical units are in one molecule?
Answer
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