density, accuracy and precision lab
Lab No.1: density, accuracy and precision
Aim: to determine the relative precision and accuracy of different glassware items by calculating the density of a known substance.
Introduction: the density of a substance is its mass per unit volume. (where P-density, m- mass and v- volume). Different materials usually have different densities and densities vary according to the pressure, temperature and purity of a substance. When measuring, there is always a small uncertainty or error and therefore no measurement is exact.
Variables:
Independent: the type of liquid used
Dependant: the volume and density of the liquid
Controlled: the same type of beaker as the mass of the beaker is never changed
Hypothesis : the larger the divisions on the glassware items the bigger the percentage of error.
Materials:
Car oil
Coke Zero
Liquid soap
Salty water
1x 200ml beaker
1 x 100ml beaker
1 x 10ml cylinder
1 x weighing scale
1 x thermometer
Procedure:
1. Weigh a dry 100 ml beaker, a 10 ml graduated cylinder and a 10 ml pipette (in this case weigh a 150 ml beaker that you will transfer into a pipette, pipettes cannot be weighted effectively) and record the mass for each case. Do not forget that trailing zeros are significant figures and should be recorded.
2. Obtain a fair amount of water and measure its temperature.
(Remember here some students are measuring different substances, so the procedure must be the same but with the substance assigned by the teacher)
3. Put 10 ml of water in each glassware item. Record the volume for each one.
4. Weigh and record the mass for each item.
5. Do this 3 times for each piece of glassware, making sure you dry (as best as you can) the glassware in between trials.
6. Consult a reference book to determine the density of water (or the substance assigned) at your observed temperature. Cite your reference properly.
Data: 10ml cylinder 100 ml beaker 200ml beaker
Weight Empty\ ±0.01g
Aim: to determine the relative precision and accuracy of different glassware items by calculating the density of a known substance.
Introduction: the density of a substance is its mass per unit volume. (where P-density, m- mass and v- volume). Different materials usually have different densities and densities vary according to the pressure, temperature and purity of a substance. When measuring, there is always a small uncertainty or error and therefore no measurement is exact.
Variables:
Independent: the type of liquid used
Dependant: the volume and density of the liquid
Controlled: the same type of beaker as the mass of the beaker is never changed
Hypothesis : the larger the divisions on the glassware items the bigger the percentage of error.
Materials:
Car oil
Coke Zero
Liquid soap
Salty water
1x 200ml beaker
1 x 100ml beaker
1 x 10ml cylinder
1 x weighing scale
1 x thermometer
Procedure:
1. Weigh a dry 100 ml beaker, a 10 ml graduated cylinder and a 10 ml pipette (in this case weigh a 150 ml beaker that you will transfer into a pipette, pipettes cannot be weighted effectively) and record the mass for each case. Do not forget that trailing zeros are significant figures and should be recorded.
2. Obtain a fair amount of water and measure its temperature.
(Remember here some students are measuring different substances, so the procedure must be the same but with the substance assigned by the teacher)
3. Put 10 ml of water in each glassware item. Record the volume for each one.
4. Weigh and record the mass for each item.
5. Do this 3 times for each piece of glassware, making sure you dry (as best as you can) the glassware in between trials.
6. Consult a reference book to determine the density of water (or the substance assigned) at your observed temperature. Cite your reference properly.
Data: 10ml cylinder 100 ml beaker 200ml beaker
Weight Empty\ ±0.01g