1.
State what is meant by n = m/M. [1]
JD SCIENCE
Laboratory chemical calculations
Answer all questions. Show working. Answers are in a separate file on the Worksheets page — do not look at them until you have finished.
2.
State what is meant by c = n/V. [1]
3.
State what is meant by a dilution. [1]
4.
State what is meant by a titration calculation. [1]
5.
State what is meant by percentage yield. [1]
6.
State what is meant by atom economy. [1]
7.
State what is meant by a standard solution. [1]
8.
State what is meant by uncertainty. [1]
9.
State what is meant by a calibration graph. [1]
10.
State what is meant by unit prefixes. [1]
11.
Noah is asked about n = m/M in a NCFE Laboratory Sciences paper.
(a) Describe n = m/M. [2]
(b) Explain why n = m/M is important in this topic. [3]
12.
Noah is asked about c = n/V in a NCFE Laboratory Sciences paper.
(a) Describe c = n/V. [2]
(b) Explain why c = n/V is important in this topic. [3]
13.
Noah is asked about a dilution in a NCFE Laboratory Sciences paper.
(a) Describe a dilution. [2]
(b) Explain why a dilution is important in this topic. [3]
14.
Noah is asked about a titration calculation in a NCFE Laboratory Sciences paper.
(a) Describe a titration calculation. [2]
(b) Explain why a titration calculation is important in this topic. [3]
15.
Noah is asked about percentage yield in a NCFE Laboratory Sciences paper.
(a) Describe percentage yield. [2]
(b) Explain why percentage yield is important in this topic. [3]
16.
Noah is asked about atom economy in a NCFE Laboratory Sciences paper.
(a) Describe atom economy. [2]
(b) Explain why atom economy is important in this topic. [3]
17.
Dilute 10.0 cm³ of 1.00 mol dm⁻³ to 250 cm³. New c? [3]
18.
25.0 cm³ of 0.100 mol dm⁻³ HCl vs NaOH. Moles HCl? [3]
19.
If that NaOH titre is 20.0 cm³, c(NaOH)? [3]
20.
Mass of 0.0500 mol of H₂SO₄ (M=98) [3]
21.
Convert 250 µg to grams [3]
22.
A graph reads 0.35 absorbance = 7.0 mg dm⁻³. What is 0.70 if linear through 0? [3]
23.
Noah carries out a T-Level occupational task on laboratory chemical calculations. This is a typical NCFE required-practical style question.
(a) Identify the independent variable and the dependent variable. [2]
(b) State one control variable and explain why it must be controlled. [2]
(c) Suggest one improvement or source of error and how it affects the result. [2]
24.
Noah carries out writing or following an SOP for laboratory chemical calculations. This is a typical NCFE required-practical style question.
(a) Identify the independent variable and the dependent variable. [2]
(b) State one control variable and explain why it must be controlled. [2]
(c) Suggest one improvement or source of error and how it affects the result. [2]
25.
Noah carries out a COSHH / risk-assessment review for laboratory chemical calculations. This is a typical NCFE required-practical style question.
(a) Identify the independent variable and the dependent variable. [2]
(b) State one control variable and explain why it must be controlled. [2]
(c) Suggest one improvement or source of error and how it affects the result. [2]
26.
Noah carries out data review in a LIMS or quality log for laboratory chemical calculations. This is a typical NCFE required-practical style question.
(a) Identify the independent variable and the dependent variable. [2]
(b) State one control variable and explain why it must be controlled. [2]
(c) Suggest one improvement or source of error and how it affects the result. [2]
27.
Compare n = m/M with a titration calculation. [4]
28.
Compare c = n/V with percentage yield. [4]
29.
Compare a dilution with atom economy. [4]
30.
Compare a titration calculation with a standard solution. [4]
31.
Apply your knowledge of a standard solution to this situation: primary standard if possible [3]
32.
Apply your knowledge of uncertainty to this situation: percentage then add [3]