Explanation:
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Answer:
D) 3.51x10²³ formula units
Explanation:
To know this, we need to calculate the molecular mass of CaO. To do that, let's use the atomic mass of each element of this compound.
Ca: 40.08 g/mol; O: 16 g/mol
With these given AM, let's calculate the molar mass of CaO:
Mm CaO = 40.08 + 16 = 56.08 g/mol
Now that we have the MM of CaO, it's time to determine the moles of CaO:
moles = mass / MM
moles = 32.7 / 56.08 = 0.5831 moles
Finally to get the formula units, we need to use the Avogadro's number which is 6.02x10²³. According to this number, 1 mole of any substance has this number of atoms, molecules or formula units. So, if we have 0.5831 moles, then the formula units will be:
FU = 0.5831 * 6.02x10²³
<h2>
FU = 3.51x10²³ formula units</h2>
Hope this helps
Qualitative I believe is right
The easiest way to do this is to assume that you have 100g of compound. Then you will have 69.9g of iron and 30.1g of oxygen.
You will need to find how many moles there are of each. Divide these masses by the molar mass of each element (for oxygen, just use the molar mass of O, not O2, as the calculation is easier with atoms than dioxygen):
69.9g / 55.845g/mol = 1.25mol Fe
30.1g / 15.999g/mol = 1.88mol O
Next, find the ratio of these 2 molar amounts. If we have 1 mole of Fe, we will have 1.88 / 1.25 = 1.50 mol O. Make everything whole numbers now: 1.50 is half of 3, so multiply both by 2. We get 2 moles of Fe to every 3 moles of O, so the empirical formula is Fe2O3.
Answer: (2)react completely in the reaction
limiting reactant determines the number of moles in a chemical reaction
excess reactant is the reactant with an excess number of moles