Chemical formulae and equationsIB MYP Sciences: Flashcards

What these 14 flashcards ask

What is a formula?
What is the formula of oxygen gas?
Name three other diatomic elements.
What are reactants?
What are products?
What does a balanced equation show?
Balance: Mg + O₂ → MgO
Balance: H₂ + O₂ → H₂O
Which numbers do you change to balance an equation?
What does conservation of mass mean?
Why does mass seem to fall when a gas is made in an open flask?
Why does a metal gain mass when it burns in air?
What does (aq) mean?
What do (s), (l) and (g) mean?

Exam questions on Chemical formulae and equations

A teacher in Lagos burns 0.24 g of magnesium ribbon in an open crucible. The shiny grey metal burns with a bright white flame and leaves a white powder, magnesium oxide. When the powder has cooled, she finds that its mass is 0.40 g.
Explain why the mass of the white powder is greater than the mass of the magnesium, even though mass is conserved in chemical reactions.2 marks
A student in Mumbai places an open flask containing calcium carbonate chips and dilute hydrochloric acid on a balance. The reaction forms calcium chloride solution, water and carbon dioxide gas. Bubbles are seen, and over three minutes the reading on the balance falls from 150.0 g to 148.9 g.
Explain why the total mass of reactants and products is the same in this reaction, even though the balance reading fell.2 marks
A student in Seoul heats 3.18 g of shiny pink-brown copper foil in an open crucible. The copper turns black. When the crucible has cooled, the black solid, copper oxide, has a mass of 3.98 g.
Write a word equation for the reaction, then a balanced symbol equation with state symbols.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).