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### Topic: sample of iron in iron ore  (Read 6892 times)

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#### zack

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##### sample of iron in iron ore
« on: January 31, 2009, 03:06:36 PM »
sample of rock: 4.034g rock iron ore: Fe2O3 rock contains .231g of iron

a. what is the percent iron in the rock?

b. how many g of Fe2O3 are in the "rock" sample?

c. what is percent Fe2O3 in sample?

a) percent is = molar mass of Fe/ molar mass of Fe2O3 times 100. = 55.85/159.7 x 100= 34.97%
b) .3497(4.034) =  1.4107g of Fe in rock sample
c) 100%  !!!!

#### macman104

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##### Re: sample of iron in iron ore
« Reply #1 on: January 31, 2009, 03:14:20 PM »
You need to look at it differently.

The rock weighs 4.034 g and it contains 0.231 g of Iron.

You can calculate the grams of Fe2O3 in the rock from the grams of Iron. (Calculate the mass percent of Iron in Fe2O3, then you can use that with the grams of Iron).

From there you can calculate the percent of Fe2O3 in the rock sample.

#### zack

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##### Re: sample of iron in iron ore
« Reply #2 on: January 31, 2009, 03:20:02 PM »
You need to look at it differently.

The rock weighs 4.034 g and it contains 0.231 g of Iron.

You can calculate the grams of Fe2O3 in the rock from the grams of Iron. (Calculate the mass percent of Iron in Fe2O3, then you can use that with the grams of Iron).

From there you can calculate the percent of Fe2O3 in the rock sample.
mass percent of iron is equall to .0231g/4.034g x 100=  5.73%

how can i use this with the grams of iron?

#### ARGOS++

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##### Re: sample of iron in iron ore
« Reply #3 on: January 31, 2009, 03:24:16 PM »
Dear zak;

a.)   Correct!    5.726% iron in the rock!
b.)   0.231g iron corresponds to how much g Fe2O3?  Name it for the moment xy grams.
c.)   How much % is xy g of 4.034 g?

I hope it will be of help to you.
Good Luck!
ARGOS++

#### zack

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##### Re: sample of iron in iron ore
« Reply #4 on: January 31, 2009, 03:30:29 PM »
Dear zak;

a.)   Correct!    5.726% iron in the rock!
b.)   0.231g iron corresponds to how much g Fe2O3?  Name it for the moment xy grams.
c.)   How much % is xy g of 4.034 g?

I hope it will be of help to you.
Good Luck!
ARGOS++

ok. 1 mole of Fe2O3 is equall to 159.7 and one mole of Fe is equall to 55.85. what do i need to start cancelling out to end with grams of fe2O3?

#### ARGOS++

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##### Re: sample of iron in iron ore
« Reply #5 on: January 31, 2009, 03:36:13 PM »

#### zack

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##### Re: sample of iron in iron ore
« Reply #6 on: January 31, 2009, 03:43:18 PM »
i did cross mulitiplication and came up with .6605g of fe203

#### ARGOS++

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##### Re: sample of iron in iron ore
« Reply #7 on: January 31, 2009, 03:46:08 PM »

Dear zak;

You only forgot now that there are two Fe in one Fe2O3!

Good Luck!
ARGOS++

#### zack

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##### Re: sample of iron in iron ore
« Reply #8 on: January 31, 2009, 03:55:14 PM »
now i have .3303g of fe203
i don't want to do cross muiltiplicaton. how can i use dimensional analysis in solving this problem

#### zack

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##### Re: sample of iron in iron ore
« Reply #9 on: January 31, 2009, 04:05:57 PM »
c) i have 8.19% of Fe2O3

#### ARGOS++

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##### Re: sample of iron in iron ore
« Reply #10 on: January 31, 2009, 04:07:31 PM »

Dear zak;

NO!,  -  the halfe of 0.6605g is 0.3303g!

Make only the partial RxN:    2Fe    --->    1Fe2O3, and that makes 2 moles of Fe goes in 1 mole Fe2O3.

So:                                  2 * 55.85g  : 1 * 159.7g    =   0.231g  :  xy g
If you control then xy g = 0.3303g Fe2O3.

c.)  Is correct!

Good Luck!
ARGOS++

#### zack

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##### Re: sample of iron in iron ore
« Reply #11 on: January 31, 2009, 04:11:47 PM »
thanks alot

#### ARGOS++

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##### Re: sample of iron in iron ore
« Reply #12 on: January 31, 2009, 04:13:15 PM »