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3 years ago

Question 24 Multiple Choice Worth 2 points) [BWS.02] Why is science important for society?

Chemistry

1 answer:

gulaghasi [49]3 years ago

3 0

Answer:

Because the scientific knowledge itself helps solve many basic human needs and it also improves how humans live and their standards. For example, without science medications wouldn´t exist and many technological devices we use now-a-days. We´re surrounded by science, we just don´t really notice it.

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The osmotic pressure of a solution containing 2.04 g of an unknown compound dissolved in 175.0 mLof solution at 25 ∘C is 2.13 at

kherson [118]

Answer: The molecular formula of the compound is $C_4H_{10}O_4$

Explanation:

To calculate the concentration of solute, we use the equation for osmotic pressure, which is:

$\pi=iMRT$

Or,

$\pi=i\times \frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}\times RT$

where,

$\pi$ = osmotic pressure of the solution = 2.13 atm

i = Van't hoff factor = 1 (for non-electrolytes)

Given mass of compound = 2.04 g

Volume of solution = 175.0 mL

R = Gas constant = $0.0821\text{ L atm }mol^{-1}K^{-1}$

T = temperature of the solution = $25^oC=[273+25]=298K$

Putting values in above equation, we get:

$2.13atm=1\times \frac{2.04\times 1000}{\text{Molar mass of compound}\times 175.0}\times 0.0821\text{ L.atm }mol^{-1}K^{-1}\times 298K\\\\\text{Molar mass of compound}=\frac{1\times 2.04\times 1000\times 0.0821\times 298}{2.13\times 175.0}=133.9g/mol$

Calculating the molecular formula:

The chemical equation for the combustion of compound having carbon, hydrogen and oxygen follows:

$C_xH_yO_z+O_2\rightarrow CO_2+H_2O$

where, 'x', 'y' and 'z' are the subscripts of carbon, hydrogen and oxygen respectively.

We are given:

Mass of $CO_2=36.26g$

Mass of $H_2O=14.85g$

We know that:

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

In 44 g of carbon dioxide, 12 g of carbon is contained.

So, in 36.26 g of carbon dioxide, $\frac{12}{44}\times 36.26=9.89g$ of carbon will be contained.

For calculating the mass of hydrogen:

In 18 g of water, 2 g of hydrogen is contained.

So, in 14.85 g of water, $\frac{2}{18}\times 14.85=1.65g$ of hydrogen will be contained.

Mass of oxygen in the compound = (22.08) - (9.89 + 1.65) = 10.54 g

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

Step 1: Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{9.89g}{12g/mole}=0.824moles$

Moles of Hydrogen = $\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{1.65g}{1g/mole}=1.65moles$

Moles of Oxygen = $\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{10.54g}{16g/mole}=0.659moles$

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 0.659 moles.

For Carbon = $\frac{0.824}{0.659}=1.25\approx 1$

For Hydrogen = $\frac{1.65}{0.659}=2.5$

For Oxygen = $\frac{0.659}{0.659}=1$

Converting the mole fraction into whole number by multiplying the mole fraction by '2'

Mole fraction of carbon = (1 × 2) = 2

Mole fraction of oxygen = (2.5 × 2) = 5

Mole fraction of hydrogen = (1 × 2) = 2

Step 3: Taking the mole ratio as their subscripts.

The ratio of C : H : O = 2 : 5 : 2

The empirical formula for the given compound is $C_2H_5O_2$

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 = 133.9 g/mol

Mass of empirical formula = 61 g/mol

Putting values in above equation, we get:

$n=\frac{133.9g/mol}{61g/mol}=2$

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

$C_{(2\times 2)}H_{(5\times 2)}O_{(2\times 2)}=C_4H_{10}O_4$

Hence, the molecular formula of the compound is $C_4H_{10}O_4$

4 0

3 years ago

Ionic compounds are normally in which physical state at room temperature?

Ivahew [28]

Ionic compounds are normally in which physical state at room temperature in solid. The answer is A.

Ionic Compounds Are Balanced. Table salt is an example of an ionic compound. Sodium and chlorineions come together to form sodium chloride, or NaCl. The sodium atom in this compound loses an electron to become Na+, while the chlorine atom gains an electron to become Cl-.

8 0

3 years ago

Read 2 more answers

What should the positive charge be on the Fe ion to balance out the -3 charge from the CI?

Dmitry [639]

Fe needs to have a positive charge of +3 to balance out -3 Cl

3 0

3 years ago

Why are the densities of corn syrup and gasoline expressed as a range of values

balu736 [363]

because gasoline changes volume as a function of temperature or because there are different grades of gasoline or because the values are given in different units of measure .

7 0

3 years ago

In the reaction N2 + 3H2 → 2NH3, what is the mole ratio of hydrogen to nitrogen?

uranmaximum [27]

Answer: The mole ratio of hydrogen to nitrogen is 3 mole: 1 mole, 3:1

Explanation:

•Mole ratios are determined using the coefficients of the substances in the balanced chemical equation. •Each coefficient represents the number of mole of each substance in the chemical reaction.

•The mole ratio can be determined by first writing out a balanced chemical equation for the reaction.

For this reaction the balanced chemical equation is

N2(g) + 3H2(g) ----> 2NH3(g)

1mol:3mol : 2mol

From the equation we can see that 1 mole of N2(g) reacts with 3 moles of H2(g) or 3 moles of H2(g) react with 1 mole of N2(g) to produce 2 moles of NH3(g).

Therefore, the mole ratio of hydrogen to nitrogen is 3 mole: 1 mole, 3:1

7 0

3 years ago