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### Topic: Need help on review sheet questions: I WILL LOVE WHOEVER HELPS ME!!!!!!!!!  (Read 5191 times)

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#### needgames4lyfe

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##### Need help on review sheet questions: I WILL LOVE WHOEVER HELPS ME!!!!!!!!!
« on: September 18, 2009, 12:27:38 PM »
Hey, we have this review sheet for my monday test. I did 80% of the questions, its just these that are stumping me. Could you answer them and show me how to do them?

1. DDT, an insecticide harmful to fish, birds, and humans, is produced by the following reaction.
2 C6H5Cl   +   C2HOCl3   →   C14H9Cl5   +   H2O
chlorobenzene      chloral      DDT
In a government lab, 1142 g of chlorobenzene is reacted with 480. g of chloral.
(a) What mass of DDT is formed?
g

(b) Which reactant is limiting?
C6H5Cl
C2HOCl3

Which is in excess?
C6H5Cl
C2HOCl3

(c) What mass of the excess reactant is left over?
g

(d) If the actual yield of DDT is 199.1 g, what is the percent yeild?
%

2.
Consider the following unbalanced reaction.
P4(s) + F2(g)  PF3(g)
How many grams of F2 are needed to produce 128 g of PF3, if the reaction has a 73.2% yield?

3.
Consider the following reaction.
4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(g)
If a container were to have 30. molecules of O2 and 30. molecules of NH3 initially, how many total molecules (reactants plus products) would be present in the container after this reaction goes to completion?

4.
The space shuttle environmental control system handles excess CO2 (which the astronauts breathe out; it is 4.0% by mass of exhaled air) by reacting it with lithium hydroxide (LiOH) pellets to form lithium carbonate (Li2CO3) and water. If there are 8 astronauts on board the shuttle, and each exhales 32 L of air per minute, how long could clean air be generated if there were 25,008 g of LiOH pellets available for each shuttle mission? Assume the density of air is 0.0010 g/mL.

5.
Over the years, the thermite reaction has been used for welding railroad rails, in incendiary bombs, and to ignite solid-fuel rocket motors. The reaction is given below.
Fe2O3(s) + 2 Al(s)  2 Fe(l) + Al2O3(s)
What masses of iron(III) oxide and aluminum must be used to produce 20.0 g iron?
aluminum
g
iron(III) oxide
g
What is the maximum mass of aluminum oxide that could be produced?

#### JGK

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##### Re: Need help on review sheet questions: I WILL LOVE WHOEVER HELPS ME!!!!!!!!!
« Reply #1 on: September 18, 2009, 01:19:01 PM »
You will need to show us any initial attempts first.

We help out, we don't do it for you
Experience is something you don't get until just after you need it.

#### kimyaa2

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##### Re: Need help on review sheet questions: I WILL LOVE WHOEVER HELPS ME!!!!!!!!!
« Reply #2 on: September 19, 2009, 05:19:55 AM »
do some work!..if you know part b of your 1st question you will  get part a.. hehe

#### needgames4lyfe

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##### Re: Need help on review sheet questions: I WILL LOVE WHOEVER HELPS ME!!!!!!!!!
« Reply #3 on: September 19, 2009, 10:24:30 AM »
Ok, I dont know how to show the work, but I worked out the answers to a few of them: Here goes

1.
a.1158.52g
b. Choice B
Choice A
c. 410.47
17.1

2.
113g

5.
a-9.66g
b-28.6g

Those are all the answesr I got. could you guys help me on part c of number 5 and numbesr 3 and 4?