ExpertEasy1 markMultiple Choice
AQA GCSE · Question 01.4 · Quantitative chemistry
How did the student calculate the mass of solid sodium chloride remaining after steps 1 to 5?
How did the student calculate the mass of solid sodium chloride remaining after steps 1 to 5?
Answer options:
A.
Mass of 25 cm³ of salt solution + mass of empty evaporating dish
B.
Mass of 25 cm³ of salt solution – mass of empty evaporating dish
C.
Mass of evaporating dish and dry contents + mass of empty evaporating dish
D.
Mass of evaporating dish and dry contents – mass of empty evaporating dish
How to approach this question
The question asks how to find the mass of *only* the solid sodium chloride.
1. Identify the measurement that gives the mass of the container + salt (this is the final mass).
2. Identify the measurement that gives the mass of the container alone (this is the initial mass).
3. To find the mass of the salt, you must subtract the mass of the container from the combined mass of the container and salt.
Full Answer
D.Mass of evaporating dish and dry contents – mass of empty evaporating dish✓ Correct
The correct answer is "Mass of evaporating dish and dry contents – mass of empty evaporating dish". This calculation subtracts the initial mass of the dish from the final mass of the dish plus the salt, isolating the mass of the salt itself.
To find the mass of a substance in a container, you must use the principle of "weighing by difference".
1. First, the mass of the empty container is measured (mass of empty evaporating dish).
2. After the process (in this case, adding the solution and evaporating the water), the mass of the container with the substance inside is measured (mass of evaporating dish and dry contents).
3. Subtracting the initial mass from the final mass removes the mass of the container, leaving only the mass of the substance.
Therefore, Mass of salt = (Mass of dish + salt) - (Mass of dish).
Common mistakes
✗ Selecting an option that adds masses instead of subtracting.
✗ Confusing the mass of the salt solution with the mass of the dry salt.
Practice the full AQA GCSE Chemistry Higher Tier Paper 2
48 questions · hints · full answers · grading
More questions from this exam
Q01.1A student investigated an aqueous solution of a salt. The student identified that the salt soluti...EasyQ01.2Describe a test to identify chloride ions. Give the result of the test.EasyQ01.3The student determined the concentration of sodium chloride in the salt solution using this metho...EasyQ01.5The student calculated the concentration of sodium chloride in the salt solution. Table 1 shows t...MediumQ02.1This question is about ammonia and nitric acid. In the Haber process ammonia is produced from nit...Easy