paper 1 questions

Question 1

C4 Name and explain two details that can be included in titration for more accurate results (4)

Answer 1

any two:

• read bottom of meniscus on burette at eye level (1)
• to obtain accurate volume of solution (1)
• add solution from burette one drop at a time near end point (1)
• to identify exactly when colour change of indicator takes place (1)
• use a white tile (1)
• easier to see exact moment of colour change (1)
• wash burette with appropriate solution before titration (1)
• to ensure burette is not contaminated (1)

Question 2

C4 Why is an iron rod used rather than a stainless steel rod in investigating corrosion/rusting? (2)

Answer 2

• stainless steel resistant to corrosion/rusting
• does not react with oxygen and water
• ss rod wouldn’t rust
• no change would occur