Conceptual
All of these are empirical formulas EXCEPT:
a) C2HO2
b) MgCl2
c) N2S3
d) C3O6
d) C3O6
empirical = fully simplified
How many moles is 5.19 x 1024 atoms of Titanium (Ti)?
Round to the nearest 0.1 and include the correct unit and substance formula.
9.1 mol Ti
The molecular formula for a substance is C4H6O2. What is the empirical formula for this substance?
C2H3O
What is the molar mass of CO2
INCLUDE THE CORRECT UNIT FOR POINTS
44.01 g/mol
12.01 + 16.00(2)
How many significant figures does the number 142900000 have?
4
If there is no decimal, trailing zeros (zeros at the end) do not count
Which of the following statements is FALSE about a mole...
a) 1 mol = 6.022 x 10 23 things
b) 1 mol = molar mass of a substance
c) 1 mol = 1 gram
d) Moles are used to count small things like atoms, molecules, particles, and formula units.
C is false
How many moles is in 32.89 grams of fluorine gas (F2)? Round to the nearest 0.01 include the correct unit and substance.
0.87 mol F2
The empirical formula for a substance is H2O. The substance has a molar mass of 54.06 g/mol. What is the molecular formula for this substance?
H6O3
What is the molar mass of Mg(NO3)2
INCLUDE THE CORRECT UNIT FOR POINTS
148.33 g/mol
24.31 + 14.01(2) + 16.00(6)
How many significant figures does 3.00 have?
3 significant figures
If there is a decimal, trailing zeros DO count. The decimal signifies that you have an exact number.
Which of these are conversion factors that you can use in stoichiometry?
a) 1 mol = 6.022 x 1023 atoms
b) 1 mol = 1 gram
c) 1 mol = molar mass (grams)
d) Both A and C
d) Both A and C
How many grams is 2.09 moles of Mercury Oxide (HgO2)?
Round to the nearest 0.1 include the correct unit and substance.
486.1 g HgO2
What is the empirical formula for a substance that is 15.8 % carbon and 84.2 % sulfur?
CS2
What is the percent by mass of sodium in NaCl?
Round to the nearest 0.1 and include the correct unit and substance.
39.3 % Na
How would you round 933.999999 to have 3 significant figures?
934
Ella wants to convert grams of Na to moles. What must go at the bottom of the conversion factor she uses?
a) 1 mol
b) 1 gram
c) 22.99 grams
d) 6.022 x 1023 atoms
c) 22.99 grams
Sally has a sample of 40.12 grams of silver (Ag). How many atoms of silver is this? Round to the nearest 0.01 include the correct unit and substance.
2.24 x 1023 atoms Ag
What is the empirical formula for a substance with 83.60 % carbon and 16.40 % hydrogen by mass?
C3H7
What is the percent composition of aluminum in Al2S3?
Round to the nearest 0.1 and include the correct unit and substance.
35.9 % Al
How would you round 12.386012 to have 4 significant figures?
12.39
Are the following statements TRUE of FALSE about molar mass
1) It is the mass of 1 mole of substance
2) It is the mass of 1 atom
3) It is the mass of 6.022 x 1023 atoms of a substance
4) It is the amount of moles in 1 gram of substance
1) TRUE
2) FALSE
3) TRUE
4) FALSE
Convert 1.25 x 1024 atoms of nitrogen(N) to grams
Round to the nearest 0.01 include the correct unit and substance.
Part 1: Calculate the empirical formula of a compound that contains 36.8% nitrogen and 63.25% oxygen.
Part 2: What is the molecular formula for this substance if it has a molar mass of 152.04 g/mol?
Part 1: N2O3
Part 2: N4O6
What is the percent by mass of oxygen in Mg(OH)2?
Round to the nearest 0.1 and include the correct unit and substance for credit.
54.9 % O
16(2) divided by
24.31 + 16.00(2) + 1.01(2)
times 100
How would you round 158.9220349 to have only 2 significant figures?
160