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2
88/44 = 2.
Medical admission · Other / specialist pathway · Chemistry
Chemical principles, reactions and calculations
Combine chemical equations, mole ratios and concentration calculations.
Original Model Test for Exam unit. These questions and suggested practice times are independent Kidemy material, not an official or past paper. Choose modules for the target programme; all listed subjects are not required for every applicant.
Learn the idea
Begin with a balanced equation. Convert mass to moles, use the coefficient ratio and convert to the requested quantity. For concentration in mol/dm³, express volume in dm³. Keep strength, concentration and amount distinct.
Worked example
For 2H2 + O2 → 2H2O, 4 mol H2 with excess O2 yields at most 4 mol water. For 0.15 mol in 0.5 dm³, concentration is 0.30 mol/dm³.
- Balance and label.
- Calculate moles and the limiting reactant.
- Check units and theoretical assumptions.
Your written practice
Show your working on paper and enter your answer here. If it does not match, compare the model and try again.
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0.2
0.3/1.5 = 0.2.
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4
−log10(10^-4)=4.
Write in your own words. A guardian or teacher should review this response.
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One mole O2 reacts with 2 mol H2, so oxygen limits the reaction and 1 mol H2 remains.
Use coefficients, not an equal-moles assumption.
Write in your own words. A guardian or teacher should review this response.
Show model answer and explanation
Gas volume changes with those conditions even for the same amount.
State conditions before using a molar volume.
Chemistry model test
Solve the questions with every mole conversion visible.
Review with a guardian or teacher
- Use balanced equations.
- State volume units.
- Distinguish theoretical yield from laboratory recovery.
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