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3 years ago

Calculate the Mr of MgO

Chemistry

1 answer:

AysviL [449]3 years ago

8 0

Answer:

40.3044 g/mol

Explanation:

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Which of the following causes a chemical change?

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Distinguish the difference between physical change or chemical change.

Should be C.

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3 years ago

I have 2 samples of solid chalk (aka calcium carbonate). Sample A has a total mass of 4.12 g and Sample B has a total mass of 19

IRINA_888 [86]

Answer:

A) Sample B has more calcium carbonate molecules

Explanation:

M = Molar mass of calcium carbonate = 100.0869 g/mol

$N_A$ = Avogadro's number = $6.022\times 10^{23}\ \text{mol}^{-1}$

For the 4.12 g sample

Moles of a substance is given by

$n=\dfrac{m}{M}\\\Rightarrow n=\dfrac{4.12}{100.0869}\\\Rightarrow n=0.0411\ \text{mol}$

Number of molecules is given by

$nN_A=0.0411\times 6.022\times 10^{23}=2.48\times 10^{22}\ \text{molecules}$

For the 19.37 g sample

$n=\dfrac{19.37}{100.0869}\\\Rightarrow n=0.193\ \text{mol}$

Number of molecules is given by

$nN_A=0.193\times 6.022\times 10^{23}=1.16\times 10^{23}\ \text{molecules}$

$1.16\times 10^{23}\ \text{molecules}>2.48\times 10^{22}\ \text{molecules}$

So, sample B has more calcium carbonate molecules.

The ratio of the elements of carbon, oxygen, calcium atoms, ions, has to be same in both the samples otherwise the samples cannot be considered as calcium carbonate. Same is applicable for impurities. If there are impurites then the sample cannot be considered as calcium carbonate.

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3 years ago

Which of these changes would be classified as producing a chemical change a. freezing water b. mixing salt and water to make a s

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Answer:

Option B , Option C and Option D

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3 years ago

Which sample of matter is classified as a solution

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Answer: Air, sea water, and carbonation dissolved in soda are all examples of homogeneous mixtures, or solutions. Hope this helps :)

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3 years ago

What is the ph for hcl and ch3cooh?

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HCL - 3.01
CH3COOH -2.4

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3 years ago