C5 Quantitative Analysis 1

Question 1

What is the relationship between molar mass, number of moles and mass?

Answer 1

Number of moles = mass/molar mass

Question 2

What is the definition of relative atomic mass of an element?

Answer 2

The average mass of an atom of the element compared to the mass of 1/12th of an atom of carbon-12.

Question 3

How would you convert cm3 to dm3 (volume)?

Answer 3

Divide by 1000

Question 4

What is the relationship between the amount in moles, concentration(mol/dm3) and volume (dm3)?

Answer 4

Amount in moles = concentration x volume

Question 5

What is GDA (guideline daily amount)?

Answer 5

Amount of energy or foodstuff to be consumed each day that should be suf cient to maintain health.

Question 6

Why might the sodium content in salt not be the same as the sodium content in the actual food?

Answer 6

Sodium may come from other sources, not just salt.

Question 7

Sketch a pH titration curve for the titration of an acid or an alkali.

Answer 7

X axis - volume of acid

Y axis - pH of mixture

Question 8

Explain the need for several consistent titre readings in titrations.

Answer 8

To make sure the final average titre reading is accurate and reliable.

Question 9

Describe the difference in colour change during a titration using a single indicator compared to a mixed indicator.

Answer 9

A single indicator will show a sudden colour change, whereas a mixed indicator will show a more gradual colour change.

Question 10

Explain why an acid-base titration should use a single indicator rather than a mixed indicator.

Answer 10

Using a single indicator will show the point of neutralisation more clearly than a mixed indicator.