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Concentration and moles for OCR A-level Chemistry

Concentration and moles

This page covers the following topics:

1. Moles

Avogadro's constant: 1 mole = 6.02 x 10ยฒยณ atoms/molecules/protons. To convert from moles to atoms (or reverse) use Avogadro's constant. Moles can also be calculated by using the pyramid (mass = moles x RFM).

Moles

1

How many moles is 4.515 ร— 10ยฒยณ atoms of a substance?

n = N/Nโ‚ = 4.515 ร— 10ยฒยณ รท (6.02 ร— 10ยฒยณ) = 0.75 mol

0.75 mol

How many moles is 4.515 ร— 10ยฒยณ atoms of a substance?

2

What is the moles of 2g of calcium carbonate (CaCOโ‚ƒ)?

2 / 100 = 0.02 mol

What is the moles of 2g of calcium carbonate (CaCOโ‚ƒ)?

3

What is a mole?

1 mol = 6.02 ร— 10ยฒยณ

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What is a mole?

4

Calculate the number of particles in 2 mol of a substance?

2 * 6.02 x 10ยฒยณ = 1.204 x 10ยฒโด

Calculate the number of particles in 2 mol of a substance?

5

Calculate the number of particles in 0.5 mol of a substance?

0.5 * 6.02 x 10ยฒยณ = 3.01 x 10ยฒยณ

Calculate the number of particles in 0.5 mol of a substance?

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