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2 years ago

What property can be used to determine if a sample is a pure substance or a mixture?

Chemistry

1 answer:

Yuliya22 [10]2 years ago

7 0

Answer:

Melting point

Explanation:

Pure substances have sharp melting and boiling points while impurities lower the melting point and raise the boiling point

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If 16.9 kg of Al2O3(s), 57.4 kg of NaOH(l), and 57.4 kg of HF(g) react completely, how many kilograms of cryolite will be produc

hodyreva [135]

Answer: 69.72 kg of cryolite will be produced.

Explanation:

The balanced chemical equation is:

$Al_2O_3(s)+6NaOH(l)+12HF(g)\rightarrow 2Na_3AlF_6+9H_2O$

To calculate the moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}$

moles of $Al_2O_3$ = $\frac{16.9\times 1000g}{102g/mol}=165.7moles$

moles of $NaOH$ = $\frac{57.4\times 1000g}{40g/mol}=1435moles$

moles of $HF$ = $\frac{57.4\times 1000g}{20g/mol}=2870moles$

As 1 mole of $Al_2O_3$ reacts with 6 moles of $NaOH$

166 moles of $Al_2O_3$ reacts with = $\frac{6}{1}\times 166=996$ moles of $NaOH$

As 1 mole of $Al_2O_3$ reacts with 12 moles of $HF$

166 moles of $Al_2O_3$ reacts with = $\frac{12}{1}\times 166=1992$ moles of $HF$

Thus $Al_2O_3$ is the limiting reagent.

As 1 mole of $Al_2O_3$ produces = 2 moles of cryolite

166 moles of $Al_2O_3$ reacts with = $\frac{2}{1}\times 166=332$ moles of cryolite

Mass of cryolite $(Na_3AlF_6)$ = $moles\times {\text {molar mass}}=332mol\times 210g/mol=69720g=69.72kg$

Thus 69.72 kg of cryolite will be produced.

8 0

2 years ago

The figure above shows the Earth at two different positions in its orbit around the Sun. Which position corresponds to summer in

Lelu [443]

Answer:

A. Position B.

Explanation:

In the summer the northern hemisphere is closer to the Sun so it's Position B.

3 0

2 years ago

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How many molecules are in 3cacl2

Travka [436]

Answer:

The molar mass and molecular weight of 3CaCl2 is 332.952.

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2 years ago

Is nuclear energy potential or kinetic energy?

astraxan [27]

Answer:

kenitic energy

Explanation:

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2 years ago

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Usually , it takes very little time for a community to develop during primary succession False True

Arte-miy333 [17]

False! Primary succession is when a community has to completely start over which takes a long time.

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2 years ago