Midterm

Safety goggles must be worn
At all times
Waste chemicals are to be disposed
In the properly labeled waste container
Make sure when heating a liquid that there is a
boiling stone
Eating and drinking is
Never allowed in the lab
If there is a fire
Yell fire and alert instructor and pull fire alarm if it is a large fire and evacuate the building
If a person is on fire
Go to the safety shower
If chemicals spill on your body
Wash your hands and arms immediately with water or go to the safety shower if the chemicals are on your body and wash your eyes at the eye wash station for 15-30 minutes if chemicals are in your eyes
The uncertainty in electronic measuring tools is
+/- 1 in the final digit displayed
The uncertainty of a digital thermometer is
+/- 0.1 degrees C
The uncertainty of a 20 mL cylinder is
+/- 0.1 mL
The uncertainty of a 400 mL beaker is
+/- 5 mL
The uncertainty of a burette is
+/- 0.01 mL
The uncertainty of a thermometer is
+/- 0.2 degrees C
The uncertainty of a ruler with mm is
+/- 0.01 cm
In addition and subtraction the amount of significant figures
Is rounded off to have the same number of decimal places as the number of decimal places in the most uncertain data used
In multiplication and division, the amount of significant figures is
Rounded off to have the same number of significant figures as the number of significant figures in the measured quantity with the least number of significant figures
If the air inlets of a Bunsen burner is opened, the flame goes from
Yellow to blue
A solution is added to a burette by
Holding the burette in an almost horizontal positon and allowing the liquid to run down the side of the burette while rotating the burette alone it long axis to allow the liquid to contact all parts of the inner surface of the burette
Properties whose values depend on the amount of sample or material. Examples are mass and volume.
Extensive physical properties
Properties whose values are independent of the amount or size of the sample. Examples are pressure and temperature.
Intensive physical properties
The mass per unit volume. Two extensive variables lead to and intensive one.
Density d = m/V
Defined for liquids and solids as the ratio of the density of a material divided by the density of water. The temperature of the water is often 4 degrees C. No units.
Specific gravity SGx = dx/dwater
The volume of a cube is
V = a^3, a = length of a side of the cube
The volume of a sphere is
V = 4/3?r^3, r = radius of sphere
The volume of a right cylinder is
V = ?r^2h, r = radius of circular cross section, h = height of the cylinder
To gauge the uncertainty in a volume measurement
The possible maximum and minimum values for the quantity based on the uncertainty in the original measurements must be calculated
The volume in a graduated cylinder is found by
Taking the difference between the initial volume and the volume with the object
The largest volume displacement is found by
Subtracting the largest final volume reading (+0.1) from the smallest initial volume reading (-0.1)
The smallest volume displacement is found by
Subtracting the smallest final volume reading (-0.1) from the largest initial volume reading (+0.1)
The largest value of the density is found by
Dividing the largest mass (+0.1) by the smallest volume of liquid delivered (-0.1)
The smallest value of the density of the liquid is found by
Dividing the smallest mass (-0.1) by the largest volume of liquid delivered (+0.1)
Relative error is
part per thousand relative error = ((dn – dave)/dave)*1000
Dalton’s atomic theory was consistent with
The experimental laws of definite composition and multiple proportions that gave it great credibility
For mole ratios
One divides the moles of each component by the number of moles of the component with the lesser or least number of moles
The formula derived from the mole ratios.
Example: 1 mole Fe and 3 moles of Br yields the formula FeBr3
The empirical formula
The amount of a product formed when 100% of the limiting reactant is converted to product
The theoretical yield
The amount of a product formed during a chemical reaction
The actual yield
((actual yield)/(theoretical yield))100
Percent yield
What is the proper method to separate mixtures
Using a filter flask, Buchner funnel, aspirator set up
Substances with the ability to react with both acids and bases are
Amphoteric
Double sulfate salts that contain two different ionic sulfate compounds in a defined ratio. Are typically hydrated compounds containing a stoichiometric amount of water molecules.
Alum
Compounds with molecules of water involved in their formula. Some of the water molecules in these compounds may be chemically bonded to the metal atoms by coordinate covalent bonds.
Hydrates
|measured – accepted|/accepted (100%)
Used for accuracy
accepted = true or standard of comparison value
smaller = greatest accuracy
larger = least accurate
Percent error
Truthfulness or closeness to an accepted value, on average
Accuracy
Repeatability of successive measurements
Precision
x

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