Lab techniques Flashcards
What is a risk?
Risk is the likelihood of harm arising from exposure to a hazard.
What does a risk assessment involved?
A risk assessment involves identifying control measures to minimise the risk.
What does COSHH stand for? And what are COSHH regulations
Control of substances hazardous to health
Regulations cover substances that are hazardous to health
What are examples of substances covered by COSHH regulations
chemicals;
products containing chemicals;
fumes;
dusts;
vapours and mists;
nanotechnology;
gases and asphyxiating gases;
biological agents.
What is considered in the COSHH assessment form?
exposure, disposal procedures and handling procedures
Why do scientist wear personal protective equipment (PPE)
reduces the risk of hazardous materials coming into contact with the skin where it could cause harm
What is a dilution?
Dilution involves reducing the concentration of a substance in a solution
What is serial dilution?
Repeated dilution from a stock solution
What are dilutions in a linear dilution series?
differ by an equal interval
What are dilutions in a log dilution series?
differ by a constant proportion
What can you use serial dilutions for?
An investigator may need to know the number of bacterial cells which are contained within an environmental sample. It is likely that there are too many cells in the sample to physically count every one; therefore, we can carry out a dilution series
What do you use a colorimeter for?
The concentration of a pigmented compound can be quantified using a colorimeter
What does a colorimeter measure?
A colorimeter measures the absorbance of specific wavelengths of light by a solution.
How does a colorimeter work?
A colorimeter works by passing a light beam, at a specific wavelength, through a cuvette containing a sample solution. Some of the light is absorbed by the sample; therefore, light of a lower intensity hits the detector and the machine will display an absorbance or transmission value.
How to calibrate a colorimeter?
To calibrate a colorimeter, a cuvette containing calibration solution (usually distilled water) is placed in the cuvette compartment and the calibrate button is pressed
What types of readings do colorimeters produce?
absorbance - how much light has been absorbed by the sample;
transmission - how much light passed through the sample without being absorbed.