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3 years ago

Heating water so that it boils is an example of _____.

Chemistry

1 answer:

Leni [432]3 years ago

4 0

Answer:

Exothermic change

Explanation:

Hope this helps and sorry if it isnt the answer you were looking for.

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A compound is 7.74% hydrogen and 92.26% carbon by mass. At 100°C a 0.6883 g sample of the gas occupies 250 mL when the pressure

ycow [4]

Answer: The molecular formula for the compound is $C_6H_6$

Explanation:

We are given:

Percentage of C = 92.26 %

Percentage of H = 7.74 %

Let the mass of compound be 100 g. So, percentages given are taken as mass.

Mass of C = 92.26 g

Mass of H = 7.74 g

To formulate the empirical formula, we need to follow some steps:

Step 1: Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{92.26g}{12g/mole}=7.68moles$

Moles of Hydrogen = $\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{7.74g}{1g/mole}=7.74moles$

Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 7.68 moles.

For Carbon = $\frac{7.68}{7.68}=1$

For Hydrogen = $\frac{7.74}{7.68}=1$

Step 3: Taking the mole ratio as their subscripts.

The ratio of C : H = 1 : 1

The empirical formula for the given compound is $CH$

Calculating the molar mass of the compound:

To calculate the molecular mass, we use the equation given by ideal gas equation:

PV = nRT

Or,

$PV=\frac{m}{M}RT$

where,

P = pressure of the gas = 820 torr

V = Volume of gas = 250 mL = 0.250 L (Conversion factor: 1 L = 1000 mL )

m = mass of gas = 0.6883 g

M = Molar mass of gas = ?

R = Gas constant = $62.3637\text{ L. torr }mol^{-1}K^{-1}$

T = temperature of the gas = $100^oC=(100+273)K=373K$

Putting values in above equation, we get:

$820torr\times 0.250L=\frac{0.6883g}{M}\times 62.3637\text{ L torr }mol^{-1}K^{-1}\times 373K\\\\M=\frac{0.6883\times 62.3637\times 373}{820\times 0.250}=78.10g/mol$

For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.

The equation used to calculate the valency is:

$n=\frac{\text{Molecular mass}}{\text{Empirical mass}}$

We are given:

Mass of molecular formula = 78.10 g/mol

Mass of empirical formula = 13 g/mol

Putting values in above equation, we get:

$n=\frac{78.10g/mol}{13g/mol}=6$

Multiplying this valency by the subscript of every element of empirical formula, we get:

$C_{(1\times 6)}H_{(1\times 6)}=C_6H_6$

Hence, the molecular formula for the compound is $C_6H_6$

8 0

3 years ago

100 cm3 of the copper sulfate solution contains 1.8 g of copper sulfate.

elixir [45]

Answer:

The mass of copper sulfate in 25 cm³ of the copper sulfate solution is 0.45 g

Explanation:

The given parameters are;

The volume of the copper sulfate solution = 100 cm³

The mass of the copper sulfate in the solution = 1.8 g

Therefore, the mass of copper sulfate in 25 cm³ of the solution is given as follows;

The mass of copper sulfate in 100 cm³ of the solution = 1.8 g

The mass of copper sulfate in 1 cm³ of the solution = 1.8 g/100 = 0.018 g

Therefore;

The mass of copper sulfate in 25 × 1 = 25 cm³ of the solution, m = 25×0.018 g = 0.45 g

∴ The mass of copper sulfate in 25 cm³ of the solution, m = 0.45 g

8 0

3 years ago

Help me plx.

lisov135 [29]

Answer:

DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person's body has the same DNA.

EXPLANATION: SO THE CORRECT ANSWER IS

"NUCLEIC ACID"

7 0

3 years ago

2 What do you notice about the location of the elements in each family?

sleet_krkn [62]

Explanation:

They are indeed placed from the far left hand side of the periodic table in almost the same column. If you step around the table between left to right, the movement of electrons rises by one. When you progress down the line, the number of power increases by the one.

7 0

3 years ago

A combination of chemical symbols and numbers to represent a substance

xenn [34]

Answer:

chemical formula

Explanation:

7 0

3 years ago

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