Unit 2: Matter
In order to be classified as matter, what two properties must be listed?
Mass and Volume
0.0052
5.2 X 10 ^ 10-3
What is the quantity for one mole of anything?
1 mole = 6.02 X 1023
Which scientist and experiment is linked to the discovery of an electron? Explain the experiment.
JJ Thompson and Cathode Ray experiment led to the discovery of negatively charges electrons. The cathode ray tube showed what appears to be a beam of light and these were negative electrons. When a positive end of a magnet was held near the beam, it attracted the beam towards it.
Unit 2: Define the Law of Conservation of Mass
Matter can undergo physical or chemical changes but matter is always conserved. Matter cannot be created or destroyed.
This type of matter has fixed volume but takes the shape of its container.
Liquid
Use sig fig rules to solve for the following:
2.3 + 5.002
7.895 / 34
7.3
0.23 or 2.3 X 10 ^ -1
If I have 46 grams of sodium (Na) use the periodic table AND the following conversion factor to determine the number of moles of sodium that I have.
1 mole Na = Molar mass of Na
You have 2 moles of Na.
46 g Na X (1 mole Na/23 g Na) = 2 moles Na
Determine the proton, neutron and electron count in an the following isotope: Boron -12
5 protons, 7 neutrons and 5 electrons
Unit 3: Comment on the y=mx + b equation and R2 value for the density lab (Al and Zn) with regards to precision and accuracy.
The m is the slope and represented the measured density of Al and Zn.
The R2 value represented the precision of the data along the best fit line.
Use the concept of bananas as well as color and mass to describe extensive and intensive properties.
Increasing the number (i.e. amount) of bananas increases the mass of the bananas. Therefore, mass is an extensive property. Cutting a banana in half and reducing the amount does not change the color of the banana and it is an intensive property.
Convert 0.03 g of gold into mg.
1 mg = 10-3 g so 30 mg of gold is the answer.
Determine the % composition of sodium (Na) in Na2O. You can round to two sig figs.
Total mass of sodium in Na2O = 23 + 23 = 46 g
Total mass = 23 + 23 + 16 = 62 g
46/62 X 100% =74%
What is the element and electron count for the following ion: Mass of 33, proton count of 7 and charge of -3.
Element is Nitrogen (7 protons)
Electron count is 3 more e- than protons for a total of 10 electrons. (Check: 7+ and 10 - = -3)
Unit 4: How many Si atoms are in a computer chip if it contains 5.68 mg of Si? Use the following conversions (you determine the order) and report to 3 sig figs.
1 mole = 6.02 X 10 23 atoms, 1 mole = molar mass (g) and 1 mg = 10-3 g, 1 mole Si = 28.09 g Si
1.22 X 1020 atoms Si
What kind of property is being listed when you read "The boiling point of an alcohol is 78 degrees C"?
What kind of property is being listed when you read that "sugar ferments in alcohol."?
Physical = boiling point
Chemical = sugar fermentation
A student measures the mass of an 8cm3 block of brown sugar and it is 12.9g. Determine the Density of the brown sugar block to two sig figs.
1.6 g/cm3
The composition of adipic acid is 49.3% C, 6.9% H, and 43.8% O (by mass). The molar mass of the compound is about 146 g/mol. What is the empirical formula?
C3H5O2
What is a diatomic element and give an example.
Diatomic elements are naturally occurring elements that exist as two atoms. Any from Br-I-N-Cl-H-O-F in the formula of X2 works. Example: Br2
Unit 5: If potassium and sulfur reaction together, what is the chemical formula and name of the ionic compound (salt) that forms?
K2S and Potassium Sulfide
Identify at least 4 indicators of a chemical change.
Heat/light evolution
Formation of gas (i.e. new product)
Color Change
Formation of a precipiate
The volume of a liquid is 15.0mL and it is supposed to be 18.8mL. Are your results accurate, not accurate? How do you know?
18.8-15/18.8 X 100 = 20% error (80% accuracy).
You are not accurate as your 80% accuracy < 95% accuracy.
Write the molecular formula for a compound that has a mass of 243.39 g and has the following percentages: 74% Carbon, 8.70 % Hydrogen and 17.3% Nitrogen.
C15H21O3
Write the nuclear equation for the beta decay of Thorium-234
You should have the nuclear notation for Thorium-234 with proton count of 90 then an arrow (-->) and the nuclear notation for a beta particle and Pa-234 with a proton count of 91.
If I have 44.8L of CO2 gas at STP, how many molecules of CO2 gas is this?
Use following conversions: 1 mole = 22.4 L of gas at STP and 1 mole = 6.022 X 1023
1.2 X 1024 molecules of CO2