LABORATORY ACTIVITIES FOR REGENTS CHEMISTRY : LABORATORY ACTIVITIES FOR REGENTS CHEMISTRY
Slide2 : Many laboratory activities require measurements.
Science uses the S.I. (Metric System) of measurements.
Types of measurements: : Types of measurements: Linear (length or distance)
Mass (weight)
Volume
Temperature
Slide4 : All measuring instruments have calibrations. These are the markings or divisions on the measuring tool.
Slide5 : Linear measurements are made using a Meter Stick or Metric Ruler. Metric Ruler Meter Stick
Slide6 : The basic unit for linear measurement is the meter (m.). Other commonly used units are the centimeter (cm.) and millimeter (mm.).
One advantage of the metric system is that everything is based on the number, 10, or some multiple of 10.
10 mm. = 1 cm. (and 1 mm. = 0.1 cm.)
100 cm. = 1 m. (and 1 cm. = 0.01 m.)
Also, 1000 m. = 1 kilogram (kg.).
Slide7 : A metric ruler cm. marks mm. marks
Slide8 : When making measurements, scientists use a concept and a practice known as significant figures (Sig. Figs.)
Slide9 : Significant figures include an estimated digit that is always one place beyond the calibrations on any measuring instrument.
Slide10 : Estimating the last digit in a measurement You might estimate the end of the cylinder to be half-way between the lines or 0.05 cm. This digit must be included in the measurement.
Slide11 : Estimating the last digit in a measurement This measurement should be read as 4.95 cm. This measurement has 3 significant figures.
Slide12 : Reading a metric ruler correctly: This point can be read as 1.65 cm. or 16.5 mm.
Slide13 : Reading a metric ruler correctly: This point can be read as 6.70 cm. or 67.0 mm.
Slide14 : Mass measurements are made using a balance.
There are several kinds of balances:
Triple beam balance
Dial-a-gram balance
Electronic/ digital balance
Analytical balance
Slide15 : The triple beam balance:
Slide16 : The dial-a-gram balance:
Slide17 : The electronic/ digital balance: When using this balance, it is not necessary to estimate any places.
Slide18 : The analytical balance: This is used for very technical, precise applications.
Slide19 : Mass, in the metric system, is measured in grams (g.), centigrams (cg.) or milligrams (mg.).
10 mg. = 1 cg. (and 1 mg. = 0.1 cg.)
100 cg. = 1 g. (and 1 cg. = 0.01 g.)
Also, 1000 g. = 1 kilogram (kg.)
Slide20 : As with all measuring instruments, Sig. Fig. Rules must be followed when reading a balance. How would you read this measurement?
Slide21 : This should be read as 105.00 grams (g.) How would you read this measurement?
Slide22 : CHEMISTRY PART DEUX
COMMON PROCEDURES : COMMON PROCEDURES Techniques used
for various
Activities
FILTRATION Purpose and Definitions : FILTRATION Purpose and Definitions
Used to separate suspensions.
Filtrate is the liquid portion which passes through the filter paper.
Residue (precipitate) is the portion which remains in the paper.
Slide25 : 1. Fold a circular piece of filter paper into quarters to form a cone.
2. Insert into a funnel and dampen
Slide26 :
Diluting Acids : Diluting Acids ALWAYS DILUTE
BY ADDING
ACID TO WATER
Do what ya oughta add the acid to the water.
Constructing Data Tables : Constructing Data Tables 1. Identify the variables in the experiment.
2. Set up tables using appropriate labels and state units of measurements.
Sample Data Table for Melting Pt. Lab. : Sample Data Table for Melting Pt. Lab. Time in sec. Temp.O C
0 0
5 1
10 4
15 9
20 15
25 15
30 15
35 15
40 18
45 24
Graphing : Graphing Label the X and Y axis
The X axis is the independent variable
(consistent variable such as time)
The Y axis is the changing variable
Slide31 : Temp. C Time in Sec. 0 5 10 15 20 25 30 35 40 45 0 4 8 12 16 20 24
Slide32 : Temp. C Time in Sec. 0 5 10 15 20 25 30 35 40 45 0 4 8 12 16 20 24
Slide33 : Temp. C Time in Sec. 0 5 10 15 20 25 30 35 40 45 0 4 8 12 16 20 24
Slide34 : Temp. C Time in Sec. 0 5 10 15 20 25 30 35 40 45 0 4 8 12 16 20 24 The melting point of this substance is 15 0C as
indicated by the plateau.
Final Review of Specific Labs : Final Review of Specific Labs
Heating / Cooling Curve
Density of solids and liquids
Solubility Curves
% Composition
Slide36 : Temp. C Time in Sec. 0 5 10 15 20 25 30 35 40 45 50 55 60 0 4 8 12 16 20 24 28 32 HEATING / COOLING CURVE Solid Liquid Gas Plateaus indicate change of phase. Two
phases co-exist Solid-liquid Liquid-gas
Slide37 : KNO3 saturated 110g @ 600C Unsaturated 135g @ 800C Super Saturated
85 g @ 400C
Slide38 : FINIS