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#### oceanmd

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« on: February 26, 2008, 07:09:40 PM »
please check 4 problems and explain if the answers are wrong. Thank you very much.
1.How many grams of CO are needed to react with an excess of Fe2O3 to produce 591g of Fe? Fe2O3+3CO=3CO2+2Fe
2.What is the limiting reagent when 135 g of Nitrogen reacts with 53.1g of hydrogen in the production of Ammonia? What is the maximum amount (in grams) of Ammonia that can be produced?
My answer: N2 is the limiting reagent, 164.27g NH3
3.A 350g sample of Al2(SO4)3 is reacted with 400 g of Ca(OH)2. What is the limiting reagent in this reaction? How much excess reagent is left over? What is the maximum amount of aluminum hydroxide that is produced?
Al2(SO4)3+3Ca(OH)2=2Al(OH)3+3CaSO4
My answer: Al2(SO4)3 is the limiting reagent, 173.39g Ca(OH)2 is left over, 159.14g Al(OH)3
4.When a mixture of sulfur and metallic silver is heated, silver sulfide is produced. What mass of silver sulfide is produced from a mixture of 3.0g Ag and 3.0 g S8?

#### agrobert

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##### Re: Please check 4 problems
« Reply #1 on: February 26, 2008, 07:30:39 PM »
You need to show your work.  If your MW's are correct and your equations are balanced you should always get the right answers for these problems.  You can check them yourself by making sure you can reverse your answer back to original values and your units should always cancel.  Chemical Forums won't be there during your test.  I'm only saying this so you can build confidence in your chemistry.
In the realm of scientific observation, luck is only granted to those who are prepared. -Louis Pasteur

#### ARGOS++

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##### Re: Please check 4 problems
« Reply #2 on: February 26, 2008, 07:38:22 PM »

Dear Oceanmd;

(Hello once again.)

Four times Ok!
But I think now you should study the next Chapter.
You can't get more then 100 points.

Good Luck!
ARGOS++