Chem Unit 4
Terms in this set (22)
1 mole of carbon is defined as 12 g
what is one mole defined in terms of carbon?
a mole of carbon has a mass of 12g and a mole of nitrogen has a mass of 14 g
what is the difference between a mole of carbon and a mole of nitrogen?
6.02 x 10^23
how many atoms are in a mole?
no, compounds have a definite proportion of the elements regardless of the amount of compound
does the mole ratio of the elements in compound depend on the mass of the compound?
55.8 g iron
what mass of iron has the same number of atoms as 58.7 g of nickel?
If the relative mass was calculated fir the following items which item would have a relative mass of 1?
originally all the elements were relative to hydrogen since hydrogen was the least massive element
relate the element masses on the periodic table to relative mass?
find the molar mass:
(NH4)2CO3 = 96.0 g/mol
find the molar mass of (NH4) 2CO3
0.15 moles NaNO3 x 85.0/ 1mol NaNO3 = 12.8g
convert from moles to grams: 0.15 mol NaNO3
0.476g of (NH4)2SO4 x 1 mol(NH4)2SO4/132.1g = 3.60 x 10^-3 moles
convert grams to mole: 0.476g (NH4)2SO4
2.50 mol O2 x 32.0g/1 mol= 80.0g O2
if you had 2.50 moles of oxygen gas, what mass of the gas would be in the sample?
the lowest whole # ratio of the elements in a compound
define empirical formula?
" from data"
what does the word empirical come from?
find the empirical formula of a compound having 31.05% B and 68.95% O
a compound is composed of 7.20 g of carbon, 1.20 g of hydrogen and 9.60 g of oxygen. find the empirical formula?
the exact formula of a molecule; giving the types of atoms and the # of each type.
define molecular compund?
which are molecular formulas?
empirical formula is C4H5ON2 it has a molar mass of 194.19 g/mol. What is the molecular formula of caffeine?
what is the molecular formula for a compound that has and empirical formula of CH3 having a molar mass of 45?
find the factor by dividing the molecular formula molar mass by the empirical molar mass. Use the factor to multiply the subscripts by to find the formula.
describe the steps to find the molecular formula from the empirical formula and the molar mass of the molecular formula.
1. find mass of elements
2. convert to moles.
3. divide by lowest mole to find mole ratio
4. multiply by factor if needed to get whole number
5. use mole ratios for subscripts in formula
list the steps to find the empirical formula?