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3 years ago

Help I don’t understand it and I need the answers

Chemistry

1 answer:

il63 [147K]3 years ago

4 0

Answer:

Demonstration 1 showed a chemical change because a new gaseous substance was formed, and demonstration 2 showed a physical change because liquid water became water vapor.

Explanation:

Chemical changes alter the chemical makeup of a subject, and a physical change only alters the appearance of a subject, not the chemical makeup.

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A liquid mixture composed of 20% CH4, 30% C2H4, 35% C2H2, and 15% C2H20. What is the average molecular weight of the mixture? a)

blondinia [14]

<u>Answer:</u> The correct answer is Option c.

<u>Explanation:</u>

We are given:

Mass percentage of $CH_4$ = 20 %

So, mole fraction of $CH_4$ = 0.2

Mass percentage of $C_2H_4$ = 30 %

So, mole fraction of $C_2H_4$ = 0.3

Mass percentage of $C_2H_2$ = 35 %

So, mole fraction of $C_2H_2$ = 0.35

Mass percentage of $C_2H_2O$ = 15 %

So, mole fraction of $C_2H_2O$ = 0.15

We know that:

Molar mass of $CH_4$ = 16 g/mol

Molar mass of $C_2H_4$ = 28 g/mol

Molar mass of $C_2H_2$ = 26 g/mol

Molar mass of $C_2H_2O$ = 48 g/mol

To calculate the average molecular mass of the mixture, we use the equation:

$\text{Average molecular weight of mixture}=\frac{_{i=1}^n\sum{\chi_im_i}}{n_i}$

where,

$\chi_i$ = mole fractions of i-th species

$m_i$ = molar masses of i-th species

$n_i$ = number of observations

Putting values in above equation:

$\text{Average molecular weight}=\frac{(\chi_{CH_4}\times M_{CH_4})+(\chi_{C_2H_4}\times M_{C_2H_4})+(\chi_{C_2H_2}\times M_{C_2H_2})+(\chi_{C_2H_2O}\times M_{C_2H_2O})}{4}$

$\text{Average molecular weight of mixture}=\frac{(0.20\times 16)+(0.30\times 28)+(0.35\times 26)+(0.15\times 42)}{4}\\\\\text{Average molecular weight of mixture}=6.75$

Hence, the correct answer is Option c.

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4 years ago

The repeating subunits that are responsible for the chance of a crystal are know as

Naddik [55]

Unit cells.
They are the smallest group of atoms that take form of a crystal and can repeat in 3 dimensions.

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In what type of reaction or process does heat flow into the system?

Ne4ueva [31]

Answer:

Endothermic

Explanation:

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what is the quotient of 8.01 grams divided by 3.127 grams expressed to the correct number of signicant figures

likoan [24]

Your going to want to round 8.01 to 8.01 and change 3.127 rounded too 3.1
then u want to take 8.0 and 3.1 and times it and u will get 24.8 or 25

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3 years ago

Read 2 more answers

¿que diferencia hay entre psicrómetro e higrómetro?

Tasya [4]

Answer:

Un higrómetro que para calcular la humedad se vale de la diferencia de temperaturas entre un termómetro con el bulbo seco y otro con el bulbo húmedo, normalmente se denomina psicrómetro.

Explanation:

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