Explain why elements and compounds are pure substances

2 answers:

8 0

<span>N2 - Element; Pure substance O2 - Element; Pure substance N2O - Compound; Pure Substance Air - Homogeneous; Solution</span>

neonofarm [45]3 years ago

6 0

<span>Elements and compounds are substances because we know exactly what is in them. Elements are only one kind of atom and have a symbol. Compounds have a formula telling us exactly how many of what kind of atom make up that compound

Solutions, homogeneous mixtures, not only contain 2 compounds, but we do not know how much of each. We can make salt water with one grain of salt in a cup of water or a drop of water in a cup of salt. Mixtures do not have a formula because they can be any concentration. </span>

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C5H12 + 8O2 → 5CO2 + 6H2O<br><br> Calculate the energy change for the reaction:

KATRIN_1 [288]

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b. + 1,073 kJ/mol
c. -4,185 kJ/mol
d. -2,826 kJ/mol
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2 NaCL + CaO = CaCL2 + Na2O

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222 grams of calcium chloride is produced.

<h3><u>Explanation</u>:</h3>

The mole concept and the chemical equation are very much closely related with each other. In the chemical reaction, the compounds or elements in both sides are balanced according to the number of atoms of each side of the reaction. So from there we can easily find the amount of reactant reacts to produce desired product.

Here we can see that 2 moles of sodium chloride produces 1 mole of calcium chloride.

So, 4 moles of sodium chloride will produce 2 moles of calcium chloride.

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Atomic weight of chlorine =35.5.

So,the molecular weight of calcium chloride = $40+ 35.5\times2$

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So 2 moles of calcium chloride weighs $111\times2$ grams = 222 grams.

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