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3 years ago

Determine which compound would lower the freezing point of water the most?

1 answer:

5 0

All those compounds are ionic.

Then they dissociate into ions when they are in water.

I will write the dissociation equations. The charges of the ions is indicated inside parenthesis.

KI -> K (+) + I (-) => two ions

K2SO4 -> 2 k(+) + SO4 (2-) -> three ions

NaCl -> Na(+) + Cl(-) => two ions

KBr -> K(+) + Br(-)

As you se every molecule of the compound K2SO4 dissociates into three ions, while the other compounds dissociate into two ions. Given that the decrase in the freezong point of water is proportional to the number of particles dissolved, the K2SO4 will lower the freezing point the most.

Answer: option B. K2SO4

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a 20.4 g aluminum sphere and a 49.4 g iron sphere are both added to 75.2 mL of water contained in a graduated cylinder. what is

alexandr1967 [171]

The level in the beaker will increase because the volumes of the spheres will also be added to the volume of the water. First, we must determine the volume of each sphere. For this, we will use:

density = mass / volume
We can check the density of both aluminum and iron in literature, and given the mass, we may obtain the volume.

Aluminum:
Density = 2.70 g/ml
Mass = 20.4 g
Volume = 20.4 / 2.7 = 7.56 ml

Iron:
Density = 7.87 g/ml
Mass = 49.4 g
Volume = 49.4 / 7.87 = 6.28 ml

Now, we add these volumes to the volume of water present:
75.2 + 6.28 + 7.56 = 89.04

The new level will be 89.0 ml

3 0

3 years ago

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The combined gas law states that

seropon [69]

Answer:

Option B. PV = nRT.

Explanation:

From the above,

C = PV / T. (1)

But, C is directly proportional to n, where R is the gas constant i.e

C & n

C = nR

Substituting the value of C into equation (1), we have:

C = PV / T

nR = PV / T

Cross multiply to express in linear form

nRT = PV

Therefore,

PV = nRT

8 0

3 years ago

The subatomic particle that has. Positive charge and is found in the nucleus an atom is

Kipish [7]

Answer:Protons, neutrons, and electrons are the three main subatomic particles found in an atom. Protons have a positive (+) charge. An easy way to remember this is to remember that both proton and positive start with the letter "P." Neutrons have no electrical charge.

Explanation:

8 0

3 years ago

What type of reaction is this? N2 + 3H2 2NH3

Levart [38]

Answer:

It is a combination reaction; nitrogen and hydrogen combine to form ammonia.

Explanation:

7 0

3 years ago

Menthol, the substance we can smell in mentholated cough drops, is composed of C, H, and O. A 0.1005 g sample of menthol is comb

Bogdan [553]

Answer: The molecular formula for the menthol is $C_{10}H_{20}O$

Explanation:

The chemical equation for the combustion of hydrocarbon 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 $CO_2=0.2829g$

Mass of $H_2O=0.1159g$

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

So, in 0.2829 g of carbon dioxide, $\frac{12}{44}\times 0.2829=0.077g$ of carbon will be contained.

For calculating the mass of hydrogen:

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

So, in 0.1159 g of water, $\frac{2}{18}\times 0.1159=0.0129g$ of hydrogen will be contained.

Mass of oxygen in the compound = (0.1005) - (0.077 + 0.0129) = 0.0106 g

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

Step 1: Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{0.077g}{12g/mole}=0.0064moles$

Moles of Hydrogen = $\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{0.0129g}{1g/mole}=0.0129moles$

Moles of Oxygen = $\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{0.0106g}{16g/mole}=0.00066moles$

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 0.00066 moles.

For Carbon = $\frac{0.0064}{0.00066}=9.69\approx 10$

For Hydrogen = $\frac{0.0129}{0.00064}=19.54\approx 20$

For Oxygen = $\frac{0.00066}{0.00066}=1$

Step 3: Taking the mole ratio as their subscripts.

The ratio of C : H : O = 10 : 20 : 1

Hence, the empirical formula for the given compound is $C_{10}H_{20}O_1=C_{10}H_{20}O$

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 = 156.27 g/mol

Mass of empirical formula = 156 g/mol

Putting values in above equation, we get:

$n=\frac{156.27g/mol}{156g/mol}=1$

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

$C_{(1\times 10)}H_{(1\times 20)}O_{(1\times 1)}=C_{10}H_{20}O$

Thus, the molecular formula for the menthol is $C_{10}H_{20}O$

4 0

3 years ago

Read 2 more answers