What is the molecular mass for a non-electrolyte if 35.0 g of it is dissolved in 45.0 grams of water and the solutions boiling point is 101.25oC? (The KB for H2O is .51°C/m)

Answers

Answer 1

The boiling point of water increases as the amount of impurities dissolved in it increases. For our purposes, we will consider the non-electrolyte to be the dissolved impurity. The change in the boiling point can be calculated using the equation:

[tex]\Delta T_b = i \times K_b \times m[/tex]

where [tex]\Delta T_b[/tex] is the change in boiling point, [tex]i[/tex] is the van ‘t Hoff factor (whose value denotes the number of particles each formula unit of the dissolved substance dissociates into in water), [tex]K_b[/tex] is the boiling point elevation constant, and [tex]m[/tex] is the molality (moles of solute/kilogram of solvent) of the solution.

Right off the bat, since we're dealing with a non-electrolyte, the dissolved substance can be assumed not to dissociate in water. So, our van ‘t Hoff factor, [tex]i[/tex], would be 1 (by contrast, the [tex]i[/tex] for an ionic compound like NaCl would be 2 since, in water, NaCl would dissociate into two particles: one Na⁺ ion and one Cl⁻ ion). We're also given our [tex]K_b[/tex], which is 0.51 °C/m.

Assuming the normal boiling point of pure water to be 100 °C (a defined value for sig fig purposes), the change in boiling point from having dissolved 35.0 g of the non-electrolyte can be obtained by subtracting 100 °C from the final—elevated—boiling point of 101.25 °C:

[tex]\Delta T_b = 101.25\text{ }^o\text{C} - 100\text{ }^o\text{C} = 1.25\text{ }^o\text{C}[/tex]

Now, recall what we're asked to determine: the molecular mass of the dissolved substance. There is one unknown left in the equation: the molality of the solution. Let's first solve for that:

[tex]m = \frac{\Delta T_b}{K_b} = \frac{1.25^\text{ o}\text{C}}{0.51^\text{ o}\text{C}/m} \\ m = 2.45 \text{ mol solute/kg water}.[/tex]

Notice that we didn't include the i since its value is 1.

Now, what would happen if we multiplied our molality by the mass of water we've been given? We would be left with the moles of solute. And what are we asked to find? The molecular mass, or the mass per mole. We can accomplish this in two steps. Remember to convert your mass of water to kilograms:

[tex]2.45 \text{ mol solute/kg water} \times 0.045 \text{ kg water} = 0.110 \text{ mol solute.}[/tex]

And, finally, we divide the mass of our solute by the number of moles of solute:

[tex]\frac{35.0 \text{ g solute}}{0.110 \text{ mol solute}} = 317.5 \text{ g/mol}[/tex]

Our answer to two significant figures (which is the number of sig figs to which our [tex]K_b[/tex] is given) would be 320 g/mol.


Related Questions

9.
Which element is most likely to conduct heat and electricity?
A. Na B. Ca C.P D. Ne

Answers

Answer:

A. Na

Explanation:

Sodium is a good conductor of electricity and heat because it has only one electron in its valence shell.

i hope this helps :)

Answer:

C.) P

Explanation:

I believe this is correct, lmk if it's not.

Volume of 8.625 g of sulphur di oxide at RTP in cm3

Answers

Answer:

The volume of 8.625 g of sulphur dioxide at RTP is approximately 3,230.84 cm³

Explanation:

The question requires the determination of the volume occupied by the gas based on the molar volume of a gas at STP

The given parameters of the sulphur dioxide, SO₂, gas are;

The mass of the given SO₂ gas = 8.625 g

The molar mass of SO₂ = 64.07 g/mol

The number of moles, 'n', in the given sample of SO₂ gas = Mass of SO₂/(Molar Mass of SO₂)

∴ The number of moles of SO₂ in the gas sample = 8.625 g/(64.07 g/mol) ≈ 0.134618386 moles

The molar volume of a gas at RTP is approximately 24 dm³/mole

24 dm³ = 24,000 cm³

∴ The molar volume of a gas at RTP is approximately 24,000 cm³/mole

The volume occupied by a gas at RTP = (The number of moles of the gas) × (The Molar Volume of a gas at RTP)

∴ The volume occupied by the 8.625 g of SO₂ gas at RTP = 0.134618386 moles × 24,000 cm³/mole ≈ 3,230.84 cm³

The volume occupied by the 8.625 g of SO₂ gas at RTP ≈ 3,230.84 cm³.

Which of these industrial processes typically involves electrolysis?
purifying water for drinking purposes
purifying copper to produce copper wiring for homes
neutralizing an acidic solution by adding a base
neutralizing a basic solution by adding an acid

Answers

Answer:

purifying copper to produce copper wiring for homes

Explanation:

Answer:

b.purifying copper to produce copper wiring for homes

Explanation:

Hold the slides for observation

Answers

What is this

Explanation

ANSWER ASAP THIS IS 6TH GRADE SCIENCE! GIVING BRAINLIEST FIVE STARS ANS A HEART!
Conduction is the transfer of thermal energy through direct contact. Convection is the transfer of thermal energy through the movement of a liquid or gas. Radiation is the transfer of thermal energy through thermal emission.

Answers

Answer:

what are you supposed to answer???

Explanation:

which one of these is NOT a unit for a reaction rate. 1) g/mL 2) M/min​

Answers

Reaction rate would have to do with time.

G/ml is not a unit of time this the answer

How many elements are in (NH4)3PO4

Answers

Answer:

4

Explanation:

There are 4 different elements in the compound (N, H, P, O) but if you want to count the number of each element then the answer is different.

In NH4, theres 1 N and 4 H, but since there are 3 NH4s then u have 3 N and 12 H. There's 1 P and 4 Os as well.

Added together u have 3 + 12 + 1 + 4 = 20 elements in total.

hope this helps!

it’s four, the answer is four

How many moles is 118 grams of Argon

Answers

Answer:

[tex]\boxed {\boxed {\sf About \ 2.96 \ moles \ of \ Argon}}[/tex]

Explanation:

To convert from grams to moles we must use the molar mass, which is found on the Periodic Table.

Argon: 39.9 g/mol

Use the molar mass as a ratio.

[tex]\frac{39.9 \ g \ Ar}{1 \ mol \ Ar}[/tex]

Multiply by the given number of grams: 118

[tex]118 \ g \ Ar *\frac{39.9 \ g \ Ar}{1 \ mol \ Ar}[/tex]

Flip the fraction so the grams of argon will cancel each other out.

[tex]118 \ g\ Ar * \frac{1 \ mol \ Ar}{39.9 \ g \ Ar}[/tex]

[tex]118 * \frac{ 1 \ mol \ Ar}{39.9 \ g \ Ar}[/tex]

[tex]\frac {118 \ mol \ Ar }{ 39.9 }[/tex]

[tex]2.95739348 \ mol \ Ar[/tex]

The original measurement of grams had 3 significant figures, so our answer must have 3 sig figs.

For the number we calculated, that is the hundredth place. The 7 in the thousandth place tells us to round the 5 to a 6.

[tex]2.96 \ mol \ Ar[/tex]

There are about 2.96 moles of Argon in 118 grams.

Use the periodic table to determine which of the
following could be an isotope of bromine (Br).
Check all that apply.
Z = 79, A = 196
Z = 35, A = 79
A = 79, N =44
D Z = 44, N = 44
DONE

Answers

A=79, N=44 lmk if I’m wrong ?

if I have a +2 oxidation number do I give up or accept electrons?​

Answers

Answer:

I will give up the electrons

Explanation:

Consider the following rules:

1. An atom loses electrons if its oxidation number is positive.

2. An atom gains electrons if its oxidation number is negative.

3. An atom neither gains nor loses electrons if its atomic number is zero.

As I have an oxidation number [tex]+2[/tex] that is oxidation number is positive, so, I will give up electrons.

Bubbles are released when nitric acid is added to a potassium carbonate solution.
What is the net ion

Answers


Hi can I have a shout out please thank you for your reply thank you for the wonderful reply thank me love


As you climb through the upper stratosphere, the temperature: increases decreases in constant

Answers

Answer:

It increases.

Explanation:

I hope this helps.

Answer:

Increases

Explanation:

Hope this helps :)

Draw a model to represent the physical property of metals known as ductility, or the ability to be drawn into a wire.

Answers

The model that represents the physical property of metals known as ductility can be seen in the image attached below.

Metals are substances that are good conductors of heat and electricity.

The term ductility is a characteristic of metal and it explains the ability of metals to be drawn into wire. it implies that metal materials can be hammered and beaten into tiny sheets of wires.

The model in the image attached below shows how gold which is metal is drawn into wires.

Learn more about metals here:

https://brainly.com/question/25090336?referrer=searchResults

describe a difference in our inner planets and outer planets​

Answers

The four inner planets have slower orbits , slower spins,no rings and they are made out of rock and metal. The four outer planets are made out of hydrogen and helium, they are called gas giants

Which of the following has the smallest atomic radius?
a B
b Al
c F
d N
e Ga

Answers

Answer:

c. F

Explanation:

As you go top to bottom down a column of the periodic table, atomic radius increases.

As you go left to right across a period of the periodic table, atomic radius decreases.

Knowing this trend, that means that the smallest atomic radius would be located in the top right of the periodic table. The closest element to that point is fluorine, or answer C.

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