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3 years ago

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2. The formula for density is where m is mass and V is volume. If the volume inside the packet decreases, what would happen to t

he density of the air inside the packet?

1 answer:

I am Lyosha [343]3 years ago

3 0

D=m/V

If the volume decreases (denominator decreases), m/V increases, so density increases.

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Match the following associations. Exothermic or endothermic

Alekssandra [29.7K]

<u>Answer:</u>

<em>1) ∆H is positive $\Rightarrow$ Endothermic </em>

<em>2) $E_p>E_r$ $\Rightarrow$ Endothermic </em>

<em>3) Energy is absorbed $\Rightarrow$ Endothermic </em>

<em>4) $E_r>E_p$ $\Rightarrow$ Exothermic </em>

<em>5) ∆H is negtive $\Rightarrow$ Exothermic </em>

<em></em>

<u>Explanation:</u>

∆H is called as enthalpy change

It is also called as Heat of reaction

Energy is required for the bond to break a bond.

Energy is released when a bond is formed.

$H_2+Cl_2>2HCl$

that is

$H-H+Cl-Cl>2H-Cl$

We see in this equation, bonds between hydrogen and chlorine molecules gets broken and on the right side bond is formed in HCl.

If energy of products greater than energy of reactants then the reaction enthalpy change is endothermic .

If energy of products lesser than energy of reactants then the reaction enthalpy change is exothermic .

For example

$\Delta H=E_p-E_r$

$=30KJ-20KJ$

$=+10KJ$

(positive hence endothermic)

$\Delta H=E_p-E_r$

$=10KJ-40KJ$

$=-30KJ$

(negative hence exothermic)

8 0

3 years ago

A 5.325g sample of methyl benzoate, a compound in perfumes , was found to contain 3.758 g of carbon, 0.316 g of hydrogen, and 1.

Alexxandr [17]

<u>Answer:</u> The empirical and molecular formula of the compound is $C_4H_4O$ and $C_8H_8O_2$ respectively

<u>Explanation:</u>

We are given:

Mass of C = 3.758 g

Mass of H = 0.316 g

Mass of O = 1.251 g

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

<u>Step 1:</u> Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{3.758g}{12g/mole}=0.313moles$

Moles of Hydrogen = $\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{0.316g}{1g/mole}=0.316moles$

Moles of Oxygen = $\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{1.251g}{16g/mole}=0.078moles$

<u>Step 2:</u> 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 0.078 moles.

For Carbon = $\frac{0.313}{0.078}=4.01\approx 4$

For Hydrogen = $\frac{0.316}{0.078}=4.05\approx 4$

For Oxygen = $\frac{0.078}{0.078}=1$

<u>Step 3:</u> Taking the mole ratio as their subscripts.

The ratio of C : H : O = 4 : 4 : 1

The empirical formula for the given compound is $C_4H_4O$

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 = 130 g/mol

Mass of empirical formula = 68 g/mol

Putting values in above equation, we get:

$n=\frac{130g/mol}{68g/mol}=1.9\approx 2$

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

$C_{(2\times 4)}H_{(2\times 4)}O_{(2\times 2)}=C_8H_8O_2$

Hence, the empirical and molecular formula of the compound is $C_4H_4O$ and $C_8H_8O_2$ respectively

4 0

3 years ago

What are groups of two or more atoms bonded together that function as a single unit?

ASHA 777 [7]

The answer is molecules

5 0

3 years ago

The energy stored in molecular bonds is called _____.

makvit [3.9K]

Correct answer is chemical energy.

Reason:

For the chemical reactions to occur, energy is to be supplied for breaking and reorganization of bonds. This energy can be in form of heat, light, etc. Since, breaking of bonds results in chemical reactions to occur, t<span>he energy stored in molecular bonds is called Chemical energy.</span>

8 0

3 years ago

Read 2 more answers

Where would you expect snow or rain to fall on a mountain

patriot [66]

You would expect snow to fail at the peak or the top because the weather is coldest there.

7 0

3 years ago