1.2 Amount of substance

Question 1

What is the definition of relative atomic mass?

Answer 1

The average mass of one atom of an element divided by 1/12 mass of one atom of C-12

Question 2

How many atoms are there in three moles of potassium?

Answer 2

1.8066x10²⁴ (3x6.022x10²³)

Question 3

What is the ideal gas equation?

Answer 3

pV=nRT

Question 4

A compound of aluminium and oxygen is made up of 52.9% aluminium by mass. What is its empirical formula?

Answer 4

Al₂O₃

Question 5

Write a balanced equation to produce aluminium oxide from aluminium and oxygen

Answer 5

4Al+3O₂→2Al₂O₃

Question 6

What is the atom economy of the production of calcium oxide(CaO) from calcium carbonate(CaCO₃)?

Answer 6

56%

Question 7

If the empirical formula of a compound is C₄H₇Br₂ and the M_r is 1074, what is the molecular formula?

Answer 7

C₂₀H₃₅Br₁₀

Question 8

How do you convert cm³ to dm³?

Answer 8

÷1000

Question 9

How do you find the M_r of a sample if you have its mass and moles?

Answer 9

Mass÷Moles=M_r

Question 10

How do you convert °C to K?

Answer 10

Add 273 from the °C value