Balanced equations, yield and atom economyAQA A-Level Chemistry: Flashcards

What these 13 flashcards ask

How do you balance an equation?
What is a spectator ion?
Ionic equation for neutralisation of a strong acid by a strong alkali?
What are the three steps of any equation calculation?
Formula linking concentration, amount and volume?
How do you find the volume of a gas from an equation?
Define percentage yield.
Define percentage atom economy.
Atom economy of C₂H₄ + H₂O → C₂H₅OH?
Why can a reaction have a high yield but a low atom economy?
Give two advantages of a high atom economy.
How do you make up a standard solution in a volumetric flask?
What are concordant titres?

Exam questions on Balanced equations, yield and atom economy

Ethanol can be manufactured by two methods. In the hydration of ethene, C₂H₄ + H₂O → C₂H₅OH. In the fermentation of glucose, C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂. Relative formula masses: C₂H₄ = 28.0, H₂O = 18.0, C₂H₅OH = 46.0, C₆H₁₂O₆ = 180.0.
A company chooses the hydration method. Explain two advantages to society and the environment of using a process with a high atom economy.2 marks
A student titrates 25.0 cm³ portions of sodium hydroxide solution with 0.100 mol dm⁻³ hydrochloric acid, using an indicator. The mean titre is 22.40 cm³.
Calculate the concentration, in mol dm⁻³, of the sodium hydroxide solution.2 marks
A student prepares a standard solution of sodium carbonate to use in a titration with hydrochloric acid. She needs 250 cm³ of a solution of concentration 0.0500 mol dm⁻³, made using anhydrous sodium carbonate, Na₂CO₃ (Mr = 106.0).
Calculate the mass of anhydrous sodium carbonate she should weigh out.3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).