Stoichiometry question 4?

Question

Note- please do not just solve these for the answer, but give a brief explanation as to how you got them, so I can refresh my memory on how to do this branch of Chemistry again. Thanks!!!

4. Burning Coal and oil in a power plant produces pollutants such as sulfur dioxide, SO2. The Sulfur-containing compound can be removed from other waste gases, however, by the following reaction:

2SO2(g) +2CaCO3(s) +O2(g) --> 2CaSO4(s) +2CO2(g)

a)name compounds involved in the reaction

b)what mass of CaCO3 is required to remove 155g of SO2?

c)what mass of CaSO4 is formed when 155g SO2 is consumed completely

______________________________________...

Thank-you!

Answer 1

a) sulfur dioxide, calcium carbonate, oxygen gas

b)

(155 g SO2)(1 mol SO2/ 64.07 g SO2)(2 mol CaCO3/ 2 mol SO2) = 2.42 mol CaCO3

To find the mass of CaCO3 required to remove 155 g of SO2 I had to use the mole to mole relationship between CaCO3 and SO2. The stoichiometric coefficients of the balanced chemical reaction tell me that for every 2 moles of SO2 there are 2 moles of CaCO3, so there is a 1:1 ratio. Of course, if I want to relate moles of SO2 to moles of CaCO3  I first have to find the moles of SO2 in 155 g of SO2. The molar mass of S is 32.07 g/mol and the molar mass of O is 16 g/mol so (32.07 + 2*16) = 64.07 g/mol

c)

(155 g SO2)(1 mol SO2/ 64.07 g SO2)(2 mol CaSO4/ 2 mol SO2)(136.15 g CaSO4/ 1 mol CaSO4) = 329.4 g CaSO4

I use the same strategy, except this time I relate moles of product (CaSO4) to moles of reactant (SO2). The ratio is still 1:1 because there are 2 moles CaSO4/ 2 mol SO2. I use the molar mass of CaSO4, which is 136.15 g/mol to find the mass of CaSO4 that is formed with SO2 is consumed.

Answer 2

a)

SO2 = sulfur dioxide

CaCO3 = Calcium carbonate

O2 = oxygen

CaSO4 = calcium sulfate

CO2 = carbon dioxide

b)

What I would recommend doing first is finding the formula weight (molar mass, molecular weight, formula mass) of each compound.  So look on the periodic table for the atomic weight of each element and add them together.

So for example, SO2 is made up of 1 atom of S and 2 atoms of O.  Add those weights together S + O + O = 32 + 16 + 16 = 64grams/mole (I've rounded the numbers)

Once you have all of the formula weights for each compound, then go ahead and start solving your answers.

For part (b), you are trying to convert 115g SO2 into grams of CaCO3.  First convert 155g SO2 into moles of SO2 by taking the grams and dividing it by the formula weight for SO2:

155g SO2 / 64g/mol SO2 = 2.42mol SO2 (remember these numbers are rounded)

In your balanced formula, the coefficient numbers are also the number of moles of each compound.  The next step involves using the balanced formula.  Take the moles of SO2 and convert it into moles of CaCO3:

2.42mol SO2 (2mol CaCO3 / 2mol SO2) = 2.42mol CaCO3

Now, convert the moles of CaCO3 into mass of CaCO3.  Do this by taking the moles and multiplying by the formula weight of CaCO3:

2.42mol CaCO3 x 100g/mol CaCO3 = 242g CaCO3 (again, I've rounded the numbers...I don't have a periodic table in front of me)

c)

This is similar to part (b).  This time, you can start with moles, since you are still working with 155g SO2.

First, convert the moles of SO2 into moles of CaSO4 by looking at the coefficient numbers in the balanced formula:

2.42mol SO2 (2 mol CaSO4 / 2mol SO2) = 2.42mol CaSO4

Then convert the moles of CaSO4 into mass of CaSO4 by using the formula weight of CaSO4:

2.42mol CaSO4 x 136g/mol CaSO4 = 329.2g CaSO4

If it'll help, I found a nice stoichiometry flowchart.  If you click on the text in the middle, it'll show an example of how to solve the problem.

http://www.crestview-richland.k12.oh.us/...

Answer 3

a) As far as naming goes, ionic compounds start with the cation, end with the anion in -ide, e.g. NaCl- Sodium Chloride.  Covalent Compounds use prefixes such as mono, di, tri etc...  e.g. CO2- Carbon dioxide. N.B. Transition metals have varying oxidation states and therefore chemists use roman numerals to denote the different oxidation states.

b)  What mass of CaCO3 reacts completely with 155g of SO2?  Find however many moles of SO2 there are in 155g of SO2 (using molar mass).  Relate it to the reaction, multiplying the moles of SO2 by (moles of CaCO3)/(moles of SO2).  Then convert the moles of CaCO3 to grams using the molar mass of CaCO3.  Hint: It's the easiest to just use dimensional analysis in one long string so you can cancel out components.

c)  Use the same method as in b, but for CaSO4 instead of CaCO3.

Good Luck with Review! :)