Moles and Concentration

Question 1

What is a mole?

Answer 1

Amount of substance is measured using a unit called the mole and given the symbol n.
The amount of substance which contains) as many particles as there are carbon atoms in 12g of 12C

Question 2

How much roughly is a mole?

Answer 2

6 x 10^23 particles (the Avogadro constant). It doesn’t matter what the particles are.

Question 3

What is the simple formula for finding the number of moles from the number of atoms or molecules?

Answer 3

Number of moles = number of particles you have/ number of particles in a mole.

Question 4

What is molar mass?

Answer 4

Molar mass is the mass of one mole of something. But the main thing to remember is that molar mass is just the same as the relative molecular mass, Mr. The only difference is you stick a ‘g mol^-1’ for grams per mole at the end

Question 5

What is the formula that connects the molar mass of a substance to the number of moles of a substance?

Answer 5

Number of moles= mass of a substance/ molar mass.

Question 6

What is the concentration of a solution?

Answer 6

The concentration of a solution is how many moles are dissolved per dm^3 of solution.

Question 7

What are the units of concentration?

Answer 7

dm^-3

Question 8

How is a solution more concentrated than another?

Answer 8

A solution that has more moles per dm^3 than another is more concentrated.

Question 9

What is the formula to fin the number of moles in a solution?

Answer 9

Number of moles = concentration x volume (in cm^3)/1000
Or
Number of moles= concentration x volume (in dm^3)

Question 10

What are the two formulas for working out the number of moles in a volume of gas?

Answer 10

Number of moles= volume in dm^3/ 24
Or
Number of moles= volume in cm^3/ 24 000

Question 11

How many cm^3 are there in one dm^3?

Answer 11

1000

Question 12

How do you work out moles given a mass?

Answer 12

Moles = mass/molar mass.