MELS500 Week 3: Lab Math and Different Types of Data used in Labs

Formula for volumes for reagent preparation

C1V1=C2V2

Define Molarity

Number of moles of solute per one litre of solution; A measure of concentration

Define Normality

Number of equivalents of solute per litre of solution

Define % Solution

Molarity of needed solution (M)

Mass of Solute (g) x 1/Molar Mass (g/mol) x 1/Final Volume of Solution (L)

Mass of Solute (g)

Molarity (M) x Final Volume of Solution (L) x Molar Mass (g/mol)

Final Volume of Solution (L)

Mass of Solute (g) x 1/Molar Mass (g/mol) x 1/Molarity (M)

Saturated Solution

Solution containing maximum amount of a particular solute that will dissolve at that temp

Supersaturated Solution

Solution containing more solute than equilibrium conditions allow

Solute

Substance which is dissolved or has gone into solution; typically a solid

Solution

Uniform homogenous mixture of two or more substances; Individual substance may be present in varying amounts

Solvent

Substance which does the dissolving; typically liquid

Standard solution

Very precise solution used in quantitative analysis; 3-4 s.f.

Lab Math

Using calculations to analyse lab results; Any math skill or technique used in laboratory science

Why do we need lab math?

To understand principles of lab tech and experiments, calculate correct amounts of reagents used in sample testing, analyse results and troubleshoot problems

When do we use lab math?

Dilutions of samples or reagents, calculating concentrations, unit conversions, calculating volumes for reagent preparation, calculating analyte amounts or rates, quality control and SD, specimen volume calculations

How much water will you add to 20 mL of concentrated hydrochloric acid to make a 20% (v/v) HCl solution?

80mL water

How much sodium chloride (NaCl) in grams is needed to make up 5% (w/v) sodium chloride solution in 100 mL of distilled water?

5g NaCl

True or false? Always add water to acid, and not vice versa.

False

What does pH stand for?

Potential of hydrogen

Acid pH range

1 to just under 7

Base pH range

7 to 14; over 7

Exponential component use in laboratory settings?

To model phenomena exhibiting growth or decay at a rate proportional to their current value; e.g. bacteria growth

hecto

10²

kilo

10³

mega

10⁶

giga

10⁹

tera

10¹²

peta

10¹⁵

deca

10¹

deci

10^-1

centi

10^-2

milli

10^-3

micro

10^-6

nano

10^-9

pico

10^-12