4. Lab Math

What are the units for deci,centi,mili,micro,nano,decka,and hecto?

10^(-1, -2, -3, -6, -9, 1, 2)

What is the rounding rule when the last number = 5?

change to the nearest even #. i.e. 6.35 → 6.4 or 6.45 → 6.4

What is the percent solution for w/v, v/v, w/w?

w/v = grams solute/ 100 mL solvent

v/v = mL solute/ 100 mL diluent

w/w = grams solute/ 100 grams diluent

What is the specific gravity?

number of grams/ml

What is the equation regarding pH and concentration?

pH=-log[H+]

How would you calculate for an amount of anhydrous chemical needed if you only have hydrated chemicals, or vice versa?

You would need to do equivalent fractions.

What is the definition of a dilution? And how is it expressed for example ¼ or 1/5 dilution?

It is the sample amount / sample amount + diluent amount
¼ dilution = 1 part sample 3 parts diluent. 1/5 dilution = 1 part sample 4 parts diluent

How does ratio differ from dilution?

Ratio explicitly describes the amount of diluent needed in the expression.
i.e. ¼ ratio is 1 part sample 4 parts diluent which = 1/5 dilution

What are titers?

measured to determine the quantity of antibody present in a sample

lowest dilution producing a + result is the titer

What is the equation for SD? Variance? Coeff of variance?

SD: square root of ((x-mean)²/n-1)

Variance: SD²

%CV: sd/mean *100

What are the confidence intervals of 1,2,3 SD in a Gaussian distribution?

68.2%, 95.5%, 99.7%