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WorksheetsUnit 8 Final Exam Review
Total questions: 25
Worksheet time: 56mins
What is Avogadro's Number? (measures molecules and atoms)
6.02 x 1023
3.145
it changes
1
Pb5Cr5O20
Find the percent composition of CaCl2?
Ca: 36.11%; Cl: 63.88%
Ca: 53.12%; Cl: 100%
Ca: 36.11%; Cl: 83.56%
Ca: 46.11%; Cl: 63.88%
How many molecules are there in 7.85 moles of CO2?
4.72x1024 Molecules of CO2
1.50x1024 Molecules of CO2
9.00x1023 Molecules of CO2
47.2 Molecules of CO2
What is the number of moles in 50.0 grams of water (H2O)?
2.78 moles
50 moles
18.02 moles
0.900 moles
How many grams are in 1.2 x 1024 atoms of C?
29.34 grams
23.94 grams
6.02 grams
1.21 grams
A compound is known to have an empirical formula of CH and a molar mass of 39.057 g/mol. What is the molecular formula?
CH
C3H3
C6H6
C6H12O6
What is the empirical formula of a compound that is 25.9% nitrogen and 74.1% oxygen?
N2O5
N2O4
NO3
N5O2
How many molecules of water are in a 821.3 g sample?
45.58 molecules
8.232 x 1025 molecules
8.909 x 1027 molecules
2.744 x 1025 molecules
A hydrate of MgCl2 is present and the following data is collected:
mass of crucible = 22.130 grams
mass of crucible + hydrate = 25.290 grams
mass of crucible and contents after heating = 23.491 grams
What is the complete formula of this hydrate?
A 15.67 g sample of a hydrate of MgCO3 was heated to drive off the water. The mass was reduced to 7.58 g. What is the formula of the hydrate?
A student performed a lab to determine the chemical formula of a hydrate. The theoretical % of H2O in the compound is 55%. However, in the lab the student only got 52%. What is a possible experimental error that could have led to a lower lab % of water in the hydrate?
The student used a sample of hydrate that was greater than in the procedure.
The student forgot to dry the washed the crucible before beginning the lab.
The student did not heat the sample long enough.
A 4.175 gram sample of a certain hydrate of copper (II) sulfate, CuSO4•xH2O, is heated until all the water is driven off. The resulting anhydrous compound weighs 3.120 grams. What is the formula of the hydrate?
CuSO4•H2O
CuSO4•3H2O
CuSO4•6H2O
CuSO4•4H2O
Calculate the percent by mass of water in the hydrate FeCl3 ⋅ 6H2O. Round percent to the tenth place.
(a)
What is the empirical formula of this substance?
C2H3
CH3
C2H6
C2H2
Which type of particles are used for ionic compounds?
atoms
molecules
formula units
Which type of particles are used for elements?
atoms
molecules
formula units
Which type of particles are used for covalent (molecular) compounds?
atoms
molecules
formula units
If you were converting from grams Z to moles Z, which conversion factor would you use?
How many formula units are in 315g of zinc perchlorate?
1.19
1.1919
7.18x1023
7.18x1025
A sample of anhydrous calcium chloride was found to be 26.23% calcium. Check all of the following that could be the contaminant.
calcium chloride dihydrate
calcium hydroxide
calcium permanganate
potassium chloride
