Limiting Reactants Flashcards
Quantitative Chemistry (19 cards)
What is observed when magnesium carbonate is placed into hydrochloric acid?
Lots of bubbles of gas are given off
What happens to the reaction when all of one of the reactants is used up?
The reaction stops
What is the reactant that is used up in a reaction called?
Limiting reactant
Why is it important to add excess reactants in a chemical reaction?
To ensure that the other reactant is used up
How is the amount of product formed related to the limiting reactant?
Directly proportional
If you halve the amount of limiting reactant, what happens to the amount of product formed?
The amount of product formed will also halve
What can be calculated using the mass of the limiting reactant and the balanced reaction equation?
The mass of a product formed in a reaction
What is the first step in calculating the mass of a product formed?
Write out the balanced equation
What do you need to calculate after writing the balanced equation?
Relative formula masses of the reactant and product
What is the formula to find the number of moles of a substance?
Moles = mass / molar mass
How do you determine the number of moles of the other substance using the balanced equation?
Look at the ratio of moles in the equation
What is the mass of a product in a reaction called?
Yield of a reaction
What are the masses calculated using the limiting reactant called?
Theoretical yields
True or False: In practice, you always get 100% of the yield.
False
Fill in the blank: The amount of product you get will be less than you calculated due to _______.
Practical limitations
What is the balanced equation for the combustion of aluminium?
4Al + 3O2 > 2Al2O3
How is the relative formula mass of Al2O3 calculated?
(2 * 27) + (3 * 16) = 102
If 135 g of aluminium is burned, how many moles of aluminium are there?
5 moles
What is the mass of 2.5 moles of aluminium oxide?
255 g
