Further quantitative chemistry

Different ways to quote concentration

moles per dm 3

grams per dm 3

How to switch between dm3 and cm3

dm3 × 1000 = cm3

cm3 / 1000 = dm3

What is a decimeter?

10cm so a dm3 is 10×10×10 = 1000cm 3

moles calculation 1

mass/molar mass

moles calculation 2

n = cv

moles = conc (dm3) x volume (dm3)

Concentraiton in grams/dm3 calculation

concentration in moles/dm3 x mr of substance

How to complete a titration calculation

1. write equation and everything we are told in question in a table

2. use n=cv to calculate moles of known species

3. use molar ratio to calculate moles of unknown species

4. use c = n/v to calculate the concentration of unknown species

mole calculation 3

volume (dm3) / 24 dm3

moles calculation 4

volume (cm3) / 24000 cm3

First way to estimate uncertainty

From instrument resolution:

Resolution = smallest quantity change that an instrument can measure

Uncertainty of a measuring instrument = +- half the resolution value

Second way to calculate uncertainty

From a range of values of repeated measurements

uncertainty = mean +- half the range (largest - smallest)