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3 years ago

Choose the number of significant figures indicated. 0.078

Chemistry

2 answers:

Feliz [49]3 years ago

5 0

Answer : The number of significant figures are, two

Explanation :

Significant figures : The figures in a number which express the value -the magnitude of a quantity to a specific degree of accuracy is known as significant digits.

Rules for significant figures:

Digits from 1 to 9 are always significant.
All non-zero numbers are always significant. For example: 654, 6.54 and 65.4 all have three significant figures.
All zero’s between integers are always significant. For example: 5005, 5.005 and 50.05 all have four significant figures.
All zero’s preceding the first integers are never significant. For example: 0.0078 has two significant figures.
All zero’s after the decimal point are always significant. For example: 4.500, 45.00 and 450.0 all have four significant figures.

The give number is, 0.078

By using rule 4, we get the number of significant figures which are '7' and '8' that means the number of significant figures are, 2

Hence, the number of significant figures are, two

MAXImum [283]3 years ago

4 0

2 significant figures

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Answer: The mass of acetic acid that can be produced is 30.24 grams

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$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

For acetaldehyde:

Given mass of acetaldehyde = 22.2 g

Molar mass of acetaldehyde = 44 g/mol

Putting values in equation 1, we get:

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Putting values in equation 1, we get:

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$2CH_3CHO(l)+O_2(g)\rightarrow 2CH_3COOH(l)$

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2 moles of acetaldehyde reacts with 1 mole of oxygen gas

So, 0.504 moles of acetaldehyde will react with = $\frac{1}{2}\times 0.504=0.252mol$ of oxygen gas

As, given amount of oxygen gas is more than the required amount. So, it is considered as an excess reagent.

Thus, acetaldehyde is considered as a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

2 moles of acetaldehyde produces 2 moles of acetic acid

So, 0.504 moles of acetaldehyde will produce = $\frac{2}{2}\times 0.504=0.504moles$ of acetic acid

Now, calculating the mass of acetic acid from equation 1, we get:

Molar mass of acetic acid = 60 g/mol

Moles of acetic acid = 0.504 moles

Putting values in equation 1, we get:

$0.504mol=\frac{\text{Mass of acetic acid}}{60g/mol}\\\\\text{Mass of acetic acid}=(0.504mol\times 60g/mol)=30.24g$

Hence, the mass of acetic acid that can be produced is 30.24 grams

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