Can someone help me determine the empirical formula of a tin-oxygen compound?

Question

Objective:

To determine the empirical formula of a tin-oxygen compound.

Procedures:

In a fume hood (for safety reasons), measure about 3g of tin in an evaporating dish and add 5 ml of nitric acid to the tin in the dish. Allow the gas to escape and then evaporate the water by heating the dish over a Bunsen burner.

The remaining compound is a tin-oxygen compound.

Sn + HNO3 --> NO2 + H2O + tin/oxygen compound

Data:

Mass of tin in dish = 3.00 g

Mass of tin-oxygen product after heating = 3.80 g

Calculations:

1. Calculate moles of tin =

2. Calculate moles of oxygen in tin-oxygen compound =

3. Molar ratio of tin to oxygen =

4. Empirical formula =

5. Name the compound _______.

6. What is the difference between an empirical and a molecular formula?

7. What are some sources of experimental error?

Thanks SO much in advance!!

Answer 1

here's some clues to help work it out:

Look up the meaning of Avogadro number (or constant).

Look up tin and oxygen molecular weight or molecular mass.

You start with 3g of tin, the compound is 3.8g, and you were given the info that the extra is oxygen, thus the oxygen content is 0.8g.

The proportion of tin to oxygen by mass is 3:0.8

You know the molar mass of tin and oxygen so you can work out the number of moles of tin vs the number of oxygen.

From that you can work out the empirical formula.

Think of the compound structure.

Look up the oxides of tin.

Look at nitrates of tin and their reactions when heated

And what happens when you heat a tin oxide? Could it possibly lose, or gain oxygen from the atmosphere?

Could it evaporate or sublime when heated?

err...sorry to bleat on...

Accuracy of the scales used to weigh the materials?

Side reactions?

Unreacted tin?

Answer 2

find moles using molar masses:

answer to #1 is  3.00 g Sn @ 118.7 g/mole = 0.0253 moles Sn

answer to # 2. is  0.80 g O @ 16 g/ mol = 0.050 moles of O

3. Molar ratio of tin to oxygen = 1:1

4. Empirical formula =  s****.>
5. Name the compound Tin (II) oxide

6. What is the difference between an empirical and a molecular

formula?  an empirical formula is the simplest whole # ratio of atoms in the compound, where as Molecular formula has the actual # of atoms in the molecule:

water: "H2O" is both its empirical & molecular formula

hydrogen peroxide: empirical is "HO", while its molecular formula is "H2O2"

7. What are some sources of experimental error?

loss of sample due to splattering in the hood during evaporation, (leads to a lower calculated grams of total compound & also a lower  # of grams for oxygen than we should have

sometimes the final compound is not totally dried, which results in a higher calculated weight for the compound & for the oxygen