Quantitative chemistry C3

A mixture contains 20 percent iron by mass what mass of iron chloride FeCl2 would you need to provide the iron ions in 50g of the mixture

Find mass of iron

calculare percentage mass of iron in iron chloride

calculate mass of iron cloride that contains 10g of iron - 10 / percentage mass /100

Uncertainty =

in am measuring instrument …

range / 2 +- half the smallest scale division

Avogadro’s constant =

What does it mean?

6.02 × 10²³ the mass of 1 mole of a substance in grams is equal to its relative formula mass.

number of moles

mass / mr

Why does mass seem to change?

gas reacts to form part of the product

gas escaped

Big numbers in front of chemical formula in a balanced equation tell you how many ______ of each substance there are.

moles

You can ______ equations by working out moles

balance

Limiting reactant

completely used up in a chemical reaction - determines amount of product made.- directly proportional

how to work out limiting reactants?

Balance equation

work out moles for each reactant

molar ratio

smallest number of moles product made - limiting reactant

mass = mr x n

Volume of Gas =

mass/mr x 24

volume = (moles)

number of moles x molar volume (24)

At room temperature one mole of any gas occupies …

24dm3

concentration =

mass of soluteg/volume of solvent dm3

number of moles of solute/volume dm3

atom economy what is it =

how much mass is wasted and how much ends up useful

mr of desired/mr of products

Percentage yield

actual yield/theoretical yield x 100

Yields are always less than 100 percent because …

some products get lost e.g reversible reactions , filtration react with gas in air

High atom economy is better because …

less waste materials used beter for the enviroment more proffitable - not wasting as much