Spectroscopy, dilutions, and micro pipetting

Lab modules cell bio 2-5

Spectroscopy

The study of the absorption and emission of light by matter

Solute

Substance that is being dissolved

Solvent

Substance that is doing the dissolving

Standard curve

A plot of known concentrations that is used to determine an unknown concentration of a substance

Dilution factor

The number that indicates how much a solution has been diluted

Diluent

Liquid (usually water) that is used to dilute a solution

Stock solution

A highly concentrated solution that can be diluted to “working concentrations” needed for experiment.

X

Symbol that represents concentration strength of a working solution or stock solution

Solution

A homogeneous mixture of two or more substances

Dilution

The process of reducing the concentration of a solute in a solution

What does a spectrophotometer measure?

Measures how much light is being absorbed by a sample. Higher concentration = higher absorbance

Absorbance vs concentration on a graph

Concentration is on the x axis, absorbance is on the y axis.

Given the equation of line of best fit for the curve, given the absorbance of a solution, how do you find the concentration?

By subbing the absorbance value in for y

What is the formula used to calculate concentrations and volumes in a dilution problem

C1V1=C2V2

1000 microliters is equal to

1 mL

100 microliters is equal to

0.1 mL

Plunger

flat circular piece of the micropipette that is used to suck up the liquid

Tip ejector

Used to remove the tips from the micropipette

Friction ring

Sets the volume for micropipette. Do not go over or under the designated range.

True or False: the plunger has two stops. First stop is how far you press down before aspirating liquid, the second is how far you press when dispensing liquid from tip.

True

True or False: It is best to touch the tip to the side of the tube or vessel in which you are dispensing the liquid. If there is already liquid inside, be sure the tip is submerged as well.

True

True or false: All micropipettes have the same p-value (the maximum volume the pipette can hold)

False. Micropipettes have different p values. Some are p100, p10, and p1000.