Formulae, equations and Amounts of substances

Question 1

Define the mole

Answer 1

The amount of substance in grams that has the same number of particles as there are atoms in 12 grams of Carbon-12

Question 2

Define relative atomic mass

Answer 2

The average mass of one atom compared to one-twelfth of the mass of an atom of carbon-12

Question 3

Define Molar Mass

Answer 3

The mass in grams of one mole of a substance given in the unit of g/mol

Question 4

what is the formula for moles

Answer 4

Mass/Mr

Question 5

What is the formula for concentration

Answer 5

moles/volume or mass/volume

Question 6

What is the formula for the volume of a gas at room temp and pressure

Answer 6

moles x 24

Question 7

what is the formula of a new diluted solution?

Answer 7

original conc x original volume/new diluted volume

Question 8

What is the difference between a random error and a systematic error?

Answer 8

random error: caused by unpredictable changes in conditions or by a difference in recording that is difficult to get right.

Systematic error: caused by the apparatus- causes reading to be too high or low.

Question 9

State the difference between a mistake and an error

Answer 9

error: the difference between an experimental and true or correct value.
Mistake: something that even a skilled operator finds difficult to avoid, but can be avoided through taking different measures.

Question 10

What is the formula for percentage error in an apparatus?

Answer 10

uncertainty/reading x 100

Question 11

How can we reduce errors?

Answer 11

• use more precise equipment
• measure larger volumes of liquid with the same accuracy.