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WARRIOR [948]
3 years ago
11

Chemistry Question! Please help ASAP!! Would really appreciate!

Chemistry
1 answer:
Ivan3 years ago
3 0
A mixture of Cu2 and CuO of mass 8.828g is reduced to copper metal with hydrogen:
Cu2O + H2 --> 2Cu + H2O
CuO + H2 --> Cu + H2O

If the mass of pure copper isolated was 7.214g, determine the percent by mass of CuO in the original sample

Let x = grams of CuO in the original sample.
y = grams of Cu2O in the original sample.

Eq. #1 x + y = 8.828 grams

Molar mass of CuO = 63.5 + 16 = 79.5 grams
Moles of CuO = x ÷ 79.5

Molar mass of Cu2O = 63.546 + 32 = 95.5 grams
Moles of Cu2O = y ÷ 95.5

According to the 2nd balanced equation, CuO + H2 --> Cu + H2O ,
1 mole of CuO produces 1 mole of Cu.
So, x ÷ 79.5 moles of CuO will produce x ÷ 79.5 moles of Cu


According to the 1st balanced equation, Cu2O + H2 --> 2Cu + H2O,
1 mole of Cu2O produces 2 moles of Cu
So, (y ÷ 95.5) moles of Cu2O will produce 2 * (y ÷ 95.5) moles of Cu

Since, the mass of pure copper isolated was 7.214 grams
Moles of Cu = (7.214 ÷ 63.5)

Moles of Cu from Cu2O + moles of Cu from CuO = total moles of Cu!!

2 * (y ÷ 95.5) + (x ÷ 79.5) = (7.214 ÷ 63.5)
Multiply by both sides by 95.5 * 79.5 * 63.5 to get rid of denominators

(2 * 79.5 * 63.5) y + (95.5 * 63.5) x = (7.214 * 95.5 * 79.5)

10,096.5 y + 6,064.25 x = 36,418.0755
Divide both sides by 6,064.25
x + 1.665 y = 6

Eq.#2 x = 6 – 1.665 y
Eq. #1 x + y = 8.828
x = 8.828 – y

8.828 – y = 6 – 1.665 y
0.665 y = 2.828
y = 4.25 grams of Cu2O
x = 8.828 – 4.25 = 4.58 grams of CuO

% CuO = (4.58 ÷ 8.828) * 100 = 51.88% CuO
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Solnce55 [7]
We assume that we have Ka= 4.2x10^-13 (missing in the question)
and when we have this equation:
H2PO4 (-) → H+  + HPO4-
and form the Ka equation we can get [H+]:
Ka= [H+] [HPO4-] / [H2PO4] and we have Ka= 4.2x10^-13 & [H2PO4-] = 0.55m
by substitution:
4.2x10^-13 = (z)(z)/ 0.55
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z= 4.81x10^-7
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when PH equation is:

PH= -㏒[H+]
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3 0
3 years ago
Isn’t urgent the first 3 will be marked BRAINIEST
bearhunter [10]

Answer:

Al2(SO4)3 and Mg(OH)2

Explanation:

1. Al has a charge of 3-, and SO4 of 2-

when you cross multiply the charges you get

Al2 and (SO4)3

*the reason theres a bracket around the sulfate ion is that the charge 3 is not for oxygen only, but the entire sulphate ion*

Hence, Al2(SO4)3

2. Mg has a charge of 2- and OH of 1-

again cross multiply

Mg (you dont need to add the 1) and (OH)2

again, the bracket around OH means the charge appiles to Oxygen AND hydrogen

hence, Mg(OH)2

7 0
3 years ago
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A 4.24 kg marble slab has the volume of 1564 cm3 What is the density in g/cm3
miskamm [114]

Answer:

The answer is

<h2>2.71 g/cm³</h2>

Explanation:

The density of a substance can be found by using the formula

density =  \frac{mass}{volume} \\

From the question

volume of marble = 1564 cm³

1 kg = 1000 g

4.24 kg = 4240 g

mass = 4240 g

The density is

density =  \frac{4240}{1564}   \\  = 2.710997442...

We have the final answer as

<h3>2.71 g/cm³</h3>

Hope this helps you

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