Amounts of Substances in Equations (OCR GCSE Chemistry A, Combined (Gateway Science Suite)): Flashcards

📚Flashcards
Amounts of Substances in Equations
Sign up to keep revising.Create a free account to study more flashcards and track your progress.

Practise the cards

10 cards from this deck

Show

What do numbers in balanced equations show?

Ratio of moles of each substance

Formula to calculate moles from mass

Moles = mass ÷ MrM_r (or ArA_r for elements)

Mole ratio Mg:HCl in Mg+2HCl→MgCl2+H2Mg + 2HCl → MgCl_2 + H_2

1:2

Moles of Mg in Mg+2HCl→MgCl2+H2Mg + 2HCl → MgCl_2 + H_2

1 mole

Moles of HCl in Mg+2HCl→MgCl2+H2Mg + 2HCl → MgCl_2 + H_2

2 moles

Moles in 6g Mg with Mr=24M_r = 24

6÷24=0.256 ÷ 24 = 0.25 moles

How to find amounts needed/produced in reactions

Use mole ratios from balanced equation

What MrM_r means

Relative molecular mass

When to use ArA_r instead of MrM_r

For elements

Moles of H2H_2 in Mg+2HCl→MgCl2+H2Mg + 2HCl → MgCl_2 + H_2

1 mole

Explore OCR GCSE Chemistry A, Combined (Gateway Science Suite) Revision Notes by Topics

Explore OCR GCSE Chemistry A, Combined (Gateway Science Suite) Model Answers by Topics

Explore OCR GCSE Chemistry A, Combined (Gateway Science Suite) Quizzes by Topics

Explore OCR GCSE Chemistry A, Combined (Gateway Science Suite) Exam Questions by Topics

Join 100,000+ GCSE students studying Flashcards with us.

Select your subjects, and get access to A+ resources today.