Molar Mass
When calculating molar mass how do I know how many digits to record?
Two decimal places... dollars and cents.
What number will you use to convert from moles to particles?
6.02x1023
When doing conversions, what number do you always write out first?
the given number in the problem
The first step in percent composition is to find the _________________.
molar mass.
To find you an empirical formula, you first convert the percent to ______________.
grams or mass.
What is the molar mass of MgO?
40.31 g.
The mole refers to the _________________ of a substance.
amount.
When doing multistep conversions what numbers do you use to convert from particles to grams?
6.02 x 1023 and molar mass
What am I going to divide each individual total by in the problem NaOH?
40.00 grams
If you are not at whole numbers after dividing each by the lowest number of moles you have to ____________ by the lowest number possible to get whole numbers.
multiply.
What is the molar mass of H2O?
18.02 g.
What is the only conversions I need to calculate the molar mass for?
moles to mass or mass to moles.
How many molecules are in 4.65 grams of H2?
1.39x1024 molecules.
When I have parentheses in my compound, what do I do with the subscript on the outside?
Multiply by the inside subscripts.
When you have whole numbers for each element what is the last step?
plug the subscripts into your formula.
What is the molar mass of Be(NO2)2?
101.03 g.
How many moles are in 2 x 1025 molecules of Water?
30 moles.
How many grams of AlN are in 3.21 x 1018 f.u.?
0.000219 grams or 2.19x10-4 grams
What is the percent composition of hydrogen in the compound H2O?
11.21%.
What is the empirical formula for each of the following molecular formulas:
a. C2H4
b. C6H12O6
c. C3H12O9
a. CH2
b. CH2O
c. CH4O3
What is the molar mass of Mg3(PO3)2?
230.87 g.
How many moles are in 5.860 grams of water?
0.3252 moles.
How many formula units are in 34.5 grams of Na2S?
2.66 x 1023 f.u.
What is the percent composition of the Calcium in the compound Ca(NO3)2?
24.42%.
What is the molecular formula for a compound with empirical formula CH4O3 and molecular molar mass of 192.122 grams?
C3H12O9.