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Lerok [7]
3 years ago
14

Suppose you were making 100.0 mL of a solution that is 0.040 M KCl. What mass of KCl should you weigh to make this solution?

Chemistry
1 answer:
scZoUnD [109]3 years ago
3 0

Answer:

mass = 0.2982 grams

Explanation:

Given that;

volume = 100.0 mL = 0.1 L

Molarity =0.040 M

Since Molarity = \frac{no of moles }{volume}

0.040 M = \frac{x}{0.1}

(x) no of moles = 0.040 × 0.1

= 0.004 moles

Also; to calculate the  mass of KCl should you weigh to make this solution;

we have;

no of moles =\frac{mass}{molar mass}

molar mass of KCl = 74.55 g/mol

∴

0.004 moles = \frac{mass}{74.55g/mol}

mass = 0.004 moles * 74.55 \frac{g}{mol}

mass = 0.2982 grams

Hence, the mass of KCl should you weigh to make this solution is  0.2982 grams

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The answer is <span>(3) 3 × 12.4 hours
</span>
To calculate this, we will use two equations:
(1/2) ^{n} =x
t_{1/2} = \frac{t}{n}
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</span>x - remained amount of the sample, in decimals
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x = 12.5% = 0.125

Thus:
<span>(1/2) ^{n} =x
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<span>t_{1/2} = 12.4
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Answer:

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