I have a few questions on how to do a few problems that I got wrong for homework.

1. If 5.28 g of tin reacted with fluorine to form 8.65 g of a metal fluoride, what is the simplest formula of the fluoride?
I know my biggest problem here was that I misread the problem and didn't see that it was a metal fluoride, so my simplest formula came out to be simply SnF2 [the correct answer is SnF4]. How do I account for the fact that the mass given of the metal fluoride is not just of the fluoride?

2. What is the total mass of products formed when 19.0 g of carbon disulfide is burned in air? What mass of carbon disulfide would have to be burned to produce a mixture of carbon disulfide and sulfur dioxide that masses 34.4 g?
CS2 + 3O2 -> CO2 + 2SO2
I got the first part right, there 43.0 g total of products.
I wasn't sure how to do the second question though.

Also, a question asked to write the formula of nitrogen oxide. After looking this up, I found that this is a general term given to any oxide of nitrogen. Why would this be wrong? N2O3

Last one:
Aspirin, C9H8O4, is prepared by reacting salicylic acid, C7H6O3, with acetic anhydride, C4H6O3, in the reaction:
C7H6O3(s) + C4H6O3(l) -> C9H8O4(s) + C2H4O2 (l)
A student is told to prepare 45.0 g of aspirin. She is told to use a 55.0% excess of acetic anhydride and to expect to get an 85.0% yield in the reaction. How many grams of each reaction should she use?
What's really tripping me up here is the percent excess in yield; i'm not sure how to incorporate it into the problem. Could someone give me a rough outline of what needs to be done?

One question per post please.

The mass of the metal fluoride is given, ans well as the mass of the metal in it. The mass of the fluoride ion is the difference between them.

Use Ratio and proportion to solve the second part of number 2.

Nitrogen oxide can have many formulas. NO would be the plainest. Normally, chemists call that Nitrogen(II) oxide, or older ancient chemists call it Nitrogen monoxide.

On the percent yield....If she wanted 45g , then use ingredents to get 45/.85 grams.

Post your work on any of this if you get stuck. We can help you through.

2 answers

52.94 g of C7H6o3

60.65 g of C4H6O3
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