Formulas T5

Question 1

Number of moles

Answer 1

Mass/mr. Concentration x volume. No. of particles/avogadro’s

Question 2

Volume of a gas

Answer 2

24 x moles

Question 3

Ideal gas equation

Answer 3

PV=nRT. P(pa). V(m^3) n(no. of moles). R(gas constant). T(temp in K)

Question 4

Kelvin

Answer 4

K= C+273

Question 5

Percentage composition of an element

Answer 5

Mr of element/Mr of compound x100

Question 6

Percentage uncertainty

Answer 6

Uncertainty/reading x100

Question 7

Uncertainty

Answer 7

Given in the question, sometimes called error. (For burettes uncertainty is x2 as you measure twice

Question 8

6 marker about error in practical

Answer 8

• the gas produced is soluble in water
• The bung wasn’t completely sealing the test tube
• The reaction started before the bung was placed
• So results aren’t accurate because they are smaller