Safety, Lab Equipment, Units and Dilutions Flashcards
What are the three basic units of measurement for length, weight and volume in the SI system?
Length = meter (m) Mass = gram (g) Volume = litre (L)
What do you do to get a deci (d) from 1 unit?
Times by 10. A deci (d) is 1/10 of 1 unit.
How many centimeters (cm) in a meter(m)?
Times by 100. A centi (c) is 1/100 of 1 unit. (Or move decimal to the right two places).
What are the seven units of the SI system?
Meter for length Kilogram for mas Mole for concentration Second for time Ampere for electric current Kelvin for temperature Candela for light intensity
What is the formula for molarity?
Molarity or moles/liter =
(gram/gram molecular weight) / 1L
What are the two parts to a dilution?
- The sample that is to be diluted.
2. The diluent used to perform the dilution, e.g. water.
What are the two parts to a solution?
- A solute, which is the part being placed into the solution.
- The solvent - the liquid which the solute is being diluted into.
What is a general description of a dilution?
Weaker solution is made from a more concentrated solution.
What is the equation for dilution ratio?
Dilution Ratio = Vs / (Vs + Vd)
where
Vs = volume of substance being diluted and
Vd = volume of diluent
How is a dilution ratio typically expressed?
It is expressed in a ratio of lowest terms. Expressed as the ratio of 1 to a number. The numerator needs to be 1.
What is the formula for concentrations of dilutions?
Original Concentration x Dilution Ratio = New Concentration
What terms or units and concentrations be described as?
Concentrations can be in %, g/L (weight per volume), M (molarity), or N (normality).
What are beakers typically used for in a med lab?
Name some characteristics
General reagent prep Allows a lot of evaporation Markings are approximate Can heat Cannot use to measure with any degree of accuracy
What are graduated cylinders used for?
Accuracy?
Measure volume of liquids.
Not as accurate as volumetric flask.
What are Erlenmeyer flasks used for?
General preparation and mixing of reagents
Good for boiling or heating (less evaporation)
Not used for critical measurements. Accuracy is similar to beaker (lines are approximate).
What are Volumetric Flasks used for?
Measures exact volume if meniscus is at the line.
Most accurate.
Used if measurement is critical.
What are funnels used for?
Aids in getting chemicals or liquids in flasks or storage bottles.
Can use with filter paper.
What are burets and clamps used for?
Glass tube (buret) with a valve near one end that deliveries known volumes of liquid. The clamp holds the buret in place. Flow of liquid is controlled by the valve. Used for analytical chemistry.
What a scoopulas used for?
Used to transfer dry chemicals usually to a weigh boat for weighing