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

Plz help thank you!!!

Answers

Answer:

1. Covalent Bond

2. Ionic Bond

Explanation:

Covalent bonds are defined as the bond in which sharing of electrons takes place between atoms. The sharing of electrons is in equal number so that it form a stable balance of attraction and repulsion between atoms. In the given example of CO2 (first image) oxygen is sharing equal number of electrons with carbon to form a stable bond called covalent bond.

Ionic bonds are formed when valence electrons are transferred to other atoms and form oppositely charged ions. In ionic bond formation, the atoms that gain electrons become negatively charged and the atoms that loses electrons become positively charged. In the given example of Ca Cl2, Ca is also giving its 2 valence electrons to each Cl and there is no stable balance of attraction and repulsion between atoms.

Hence, the correct answer is:

1. Covalent Bond

2. Ionic Bond

What is the maximum number of electrons that an S orbital can have?
1 electron
2 electrons
4 electrons
3 electrons

Answers

S orbit can hold 2 electrons
S orbitals can have up to 2 electrons because they have one sub level and each sub level can hold up to 2 electrons

can someone please help me with this question for chemistry. What is the number of moles in 1216 g Sr3(PO4)2? the 3,4, and 2 and small numbers that go under the letters btw

Answers

2.68 mol should be the answer

Which of the following is the best representation of a heterogeneous mixture ?
A; sand and water
B; perfume
C; Gatorade
D; koolaid and water

Answers

Answer:

a)

Explanation:

2C3H7OH + 9O2 -> 6CO2 + 8H2O

How Many Moles of CO2 can be produced by reacting 6 moles of C3H7OH with oxygen?

Answers

Answer:

Up to [tex]18\; \rm mol[/tex] [tex]\rm CO_2[/tex].

Explanation:

The equation for this reaction: [tex]2\; \rm C_3 H_7 OH + 9\; O_2 \to 6\; CO_2 + 8\; H_2O[/tex] is indeed balanced.

Notice that the coefficient of [tex]\rm C_3 H_7 OH[/tex] is [tex]2[/tex] while that of [tex]\rm CO_2[/tex] is [tex]6[/tex].

Therefore, each unit of this reaction would consume [tex]2[/tex] units of [tex]\rm C_3H_7OH[/tex] while producing [tex]6[/tex] units of [tex]\rm CO_2[/tex]. In other words, this reaction would produce three times as much [tex]\rm CO_2\![/tex] as it consumes [tex]\rm C_3H_7OH\![/tex].

If all that [tex]6\; \rm mol[/tex] of [tex]\rm C_3H_7OH[/tex] molecules are actually consumed through this reaction, three times as many [tex]\rm CO_2[/tex] molecules would be produced. That corresponds to [tex]3 \times 6\; \rm mol = 18\; \rm mol[/tex] of [tex]\rm CO_2\![/tex] molecules.

What is the solvent in a salt solution like
brine?​

Answers

Answer:

in a salt solution, water is the solvent. during dissolving, particles of solvent collide with particles of solute. they sorround the particles of solute, gradually moving them away until the particles are evenly spread through the solvent.

Explanation:

HOPE IT HELPS PO(◍•ᴗ•◍)❤

1. What is a food web?
A group of animals
a food chain with two levels
A producer and consumer relationship
how several food chains are related

Answers

Answer:

a producer and consumer relationship how several food chains and related.

Answer:

The answer is:

Explanation:

A food chain with two levels.

Hope this helps!!

❤️

:)

Which characteristic describes the traposphere

Answers

Answer:

It is the wettest layer of the atmosphere.It extends upto 10km upward from sea level.

What is the chemical formula for Tetrasulfur pentoxide?

Answers

Answer:

S 4 O 5

Explanation:

the 4 and 5 are little

Which set of data is more precise?
O 1, 2, 1, 2
O 1,1.5, 1.5, 1
O 0.5, 1, 2,1.5
O 1, 2, 2, 1.5

Answers

Answer:

01,1.5,1.5,1

Explanation:

If the object is falling under the influence of gravity alone, this is called?

Answers

Answer: gravitational energy

Explanation: If you have a book on a table and it might fall, its using gravitational energy because its depending on gravity to choose rather it will fall or just balance. It also depends on how high the object is off the ground

how many grams are in 7.4 moles of HgS?

Answers

Answer:  1721.6 grams

Explanation:

Five moles of trucks would be____trucks.

Answers

Answer:

3.02x10²⁴

Explanation:

To solve this problem we need to use Avogadro's number: It is the number of units (usually atoms or molecules, in this case it's trucks) contained in one mol: 6.023x10²³.

We multiply the given number of moles times Avogadro's number:

5 * 6.023x10²³ = 3.02x10²⁴

So five moles of trucks would be 3.02x10²⁴ trucks.

How many minutes are in 180,0 days?

Answers

Answer:

259,200 minutes

Explanation:

These organs are just containers for air?
Respiratory system

Answers

The answer is lungs. Hope this helps!

What mantle is forced down and begins to melt?


HELP!

Answers

Answer:

magma

Explanation:

Answer:

magma rises through it.

Explanation:

In metallic bonds, electrons are referred to as electrons.​

Answers

Answer:

Metallic bonding may be described as the sharing of free electrons among a lattice of positively charged metal ions. The structure of metallic bonds is very different from that of covalent and ionic bonds. ... In metallic bonds, the valence electrons from the s and p orbitals of the interacting metal atoms delocalize.

165g= ______________ kg

Answers

Answer:

Hi

Explanation:

Hi

help me plz i’ll give extra points

Answers

False is the answer :) hope I helped

What was Rutherford's model of the atom missing?

Answers

Answer:

The Rutherford atomic model stated that an atom is mostly an empty space that consist of nucleus and electrons, where nucleus is positively charged and electrons are negatively charged.

But Rutherford atomic model missed to add the quantum mechanics or energy level for electrons. Rutherford was unable to make understand the planetary movement of electrons around nucleus and later Bohr's model explained it.

Hence,  Rutherford's model of the atom missed to explain the planetary movement of electrons around nucleus.

A wavelength with a frequency of 14 HZ has a wavelength of 3 meters at what speed will this wave travel

Answers

Answer:

The speed will be 42 m/s

Explanation:

Wavelength is the minimum distance between two points on the wave that are in the same state of vibration. In other words, in a periodic wave the wavelength is the physical distance between two points from which the wave repeats.

Frequency (f) is the measure of the number of cycles or repetitions of the wave per unit of time. That is, it is the number of vibrations that occur in a unit of time. That is, how many peaks or valleys are repeated in a unit of time. If the unit of time is one second then the frequency is measured in Hertz (Hz).

The wavelength (λ) and the frequency (f) are two inversely proportional parameters and related by the propagation speed. The speed of propagation is the speed with which the wave travels, it is represented by the letter "v". The equation that links these three parameters is v = f * λ.

In this case:

f= 14 Hzλ= 3 m

Replacing:

v= 14 Hz* 3 m

Solving:

v= 42 m/s

The speed will be 42 m/s

What is the phenotype of a plant with the genotype RR?
Red
White
O
Pink

Answers

Answer:

This question is incomplete, but it can be answered based on general knowledge of the topic. The answer is RED

Explanation:

This question is describing a gene that codes for color. The allele for red color is R while that of white is r, however, these two alleles exhibit incomplete dominance to form an intermediate phenotype that is PINK (Rr).

Since the heterozygous is pink color, it will take two red alleles to make a plant phenotypically red i.e RR. Note that, genotype "rr" will be white.

Define unknown solutions

Answers

Answer:

A titration is a technique where a solution of known concentration is used to determine the concentration of an unknown solution. Typically, the titrant (the know solution) is added from a buret to a known quantity of the analyte until the reaction is complete

What is the mass of 1.9 x 10^22 molecules of CaCO3?

Answers

Answer:

3.2 g CaCO₃

General Formulas and Concepts:

Math

Pre-Algebra

Order of Operations: BPEMDAS

Brackets Parenthesis Exponents Multiplication Division Addition Subtraction Left to Right

Chemistry

Atomic Structure

Reading a Periodic TableAvogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

Stoichiometry

Using Dimensional AnalysisExplanation:

Step 1: Define

1.9 × 10²² molecules CaCO₃

Step 2: Identify Conversions

Avogadro's Number

[PT] Molar Mass of Ca - 40.08 g/mol

[PT] Molar Mass of C - 12.01 g/mol

[PT] Molar Mass of O - 16.00 g/mol

Molar Mass of CaCO₃ - 40.08 + 12.01 + 3(16.00) = 100.09 g/mol

Step 3: Convert

Set up:                              [tex]\displaystyle 1.9 \cdot 10^{22} \ molecules \ CaCO_3(\frac{1 \ mol \ CaCO_3}{6.022 \cdot 10^{23} \ molecules \ CaCO_3})(\frac{100.09 \ g \ CaCO_3}{1 \ mol \ CaCO_3})[/tex]Multiply/Divide:                                                                                                    [tex]\displaystyle 3.15794 \ g \ CaCO_3[/tex]

Step 4: Check

Follow sig fig rules and round. We are given 2 sig figs.

3.15794 g CaCO₃ ≈ 3.2 g CaCO₃

List the primary consumers in the food web please help

Answers

Answer:

Giraffe, rhinoceros, grasshopper, mouse, and deer

Explanation:

Primary consumers eat producers (plants). Therefore, all the animals that eat the plants are primary consumers.

Answer:

cricket, mouse, snake, bird

Explanation:

takes Mrs. Pare' three hours to drive 175 miles from her house in Pennsylvania to her house in Maryland. What is her average speed?

Answers

Answer:58.33mph

Explanation:

Calculate the density (g/ml) of mineral that has volume (total space occupied by something) of 3.8 ml and a mass of 22.4 g.

A- 5.9 g/ml
B- 85.1 g/ml
C- 0.17 g/ml
D- 26.2g/ml

Answers

Answer:

D

Explanation:

Please help!! I'll name you brainliest!!

Answers

Answer:

H20 Covalent bond

Kl Ionic bond

NaBr ionic bond

Co2 Covalent bond

MgCl2 ionic bond

HCl Covalent bond

Explanation:

FOR 40 points!!!! I need the whole page finish !!!!!! Pleaseeeeee!!!!!!! I will five u brainlist !!!!!!

Answers

Can you help meee with mine

need points & are good at science?

Answers

Answer:

A

Explanation:

I believe the Correct answer would be A

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