0973 03 Stoichiometry CORE

Front

How does the mass of the products of a chemical reaction compare to the mass of the reactants?

Back

The mass of the products of a chemical reaction is equal to the mass of the reactants

Front

How can the mass of a reactant in a chemical reaction be calculated when the masses of the other substances in the reaction are known?

Back

Subtract the sum of the known masses of any other reactants from the sum of the known masses of the products

Front

What is the mass of one mole of any substance equal to?

Back

The substance’s relative formula mass (Mr), or relative atomic mass (Ar), in grams

Front

What do the numbers in front of substances in equations mean in terms of moles?

Back

How many moles of the substance are involved in the reaction

Front

Define molecular formula

Back

The actual numbers of elements (atoms) that are in a compound

Front

Define relative atomic mass

Back

The average mass of naturally occurring atoms of an element compared to 1/12th of the mass of an atom of carbon-12.

Front

Define relative molecular mass

Back

The sum of the relative atomic masses (Ar) of the atoms shown in the formula of a compound

Front

What is this a unit of, g/dm³?

Back

Concentration

Front

What is the end-point of a titration?

Back

When just enough of one solution has been added to completely react with the other solution.

Front

Give a brief method for carrying out a titration to find the volume of an acid needed to neutralise a known volume of an alkali.

Back

1. Put the alkali in a conical flask using a volumetric pipette 2. Add a few drops of indicator to the flask, swirl, then sit it on a white tile 3. Put a burette over the flask, then carefully fill the burette with acid 4. Add small amounts of acid to the flask and swirl, until nearly at the end-point. Stop adding acid when the indicator just changes colour.