1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Serga [27]
3 years ago
10

in order to find the molar mass of an unknown compound, a research scientist prepared a solution of 0.930 g of an unknown in 125

g of a solvent. The pure solvent had a freezing point of 74.2 degrees celcius, and the solution had a freezing point of 73.4 degrees celcius. Given the solvents freezing point depreesion contant, Kf=5.50 degrees celcius/m, find the molar mass of the unknown
Chemistry
1 answer:
PtichkaEL [24]3 years ago
3 0

Answer:

Molar mass→ 0.930 g / 6.45×10⁻³ mol = 144.15 g/mol

Explanation:

Let's apply the formula for freezing point depression:

ΔT = Kf . m

ΔT = 74.2°C - 73.4°C → 0.8°C

Difference between the freezing T° of pure solvent and freezing T° of solution

Kf = Cryoscopic constant → 5.5°C/m

So, if we replace in the formula

ΔT = Kf . m → ΔT / Kf = m

0.8°C / 5.5 m/°C = m → 0.0516 mol/kg

These are the moles in 1 kg of solvent so let's find out the moles in our mass of solvent which is 0.125 kg

0.0516 mol/kg . 0.125 kg = 6.45×10⁻³ moles. Now we can determine the molar mass:

Molar mass (mol/kg) → 0.930 g / 6.45×10⁻³ mol = 144.15 g/mol

You might be interested in
Complete the mechanism for the reaction by adding the missing curved arrows, atoms, bonds, charges, and nonbonding electron pair
Keith_Richards [23]

Answer:

See explanation below

Explanation:

In picture 1 attached, we have the starting structure. In picture 2, you have the answer for this.

Basically this is an acid base reaction to promove then, a condensation of the molecule.

In the first step, the carbonile substract a H atom from the HCl. Then, by resonance the OH+, pass the charge to the carbon, which is tertiary and can be easily stabilized. Now, after this, the Chlorine substract an Hydrogen to get a double bond on the carbon with the charge, and this be stable. Now, a second molecule of benzaldehyde reacts with this, so we can have a condensation product.

See picture 2 for complete mechanism.

4 0
3 years ago
What is another name for the representives elements?
Art [367]
Representative elements are also known as Group A elements.
7 0
3 years ago
Problem 1. (Temperature and thermal equilibrium) Temperature is an indicator of: a. Total energy of the molecules in the system
horrorfan [7]

Answer:

The average kinetic energy of the molecules in the system

Explanation:

According to the kinetic theory of matter, the particles of a system are in constant motion and collide steadily with one another as well as with the walls of the container.

The average kinetic energy of these molecules in motion is referred to as the temperature of the body. Hence, temperature is a measure of the average kinetic energy of the molecules of a body.

6 0
3 years ago
Students heat water in a beaker and measure its temperature. The starting temperature of the water was 23.3 °C. The diagram show
serious [3.7K]

Answer:

As heat is applied to liquid water, the molecules move faster and the temperature again increases. During the phase change from liquid to gas, the added heat is stored in the molecules as, once again, potential energy, and the temperature remains constant.

Explanation:

5 0
2 years ago
The first person who suggested that matter was made up of atoms was the Greek philosopher ____________________ .
abruzzese [7]

Answer:

Democritus

Explanation:

4 0
3 years ago
Read 2 more answers
Other questions:
  • An alcohol consists of an "R" group combined with the:
    6·2 answers
  • Determine the specific heat capacity of an alloy that requires 59.3 kj to raise the temperature of 150.0 g alloy from 298 k to 3
    14·1 answer
  • What is the dropping of a sediment called
    6·2 answers
  • Reasons for good care on computer​
    14·1 answer
  • Positive oxidation number suggest that the element wants to ____ (lose/gain) electrons?
    11·1 answer
  • Transmission occurs when waves pass through...
    5·1 answer
  • Under which conditions will sugar most likely dissolve fastest in a cup of water?
    8·2 answers
  • Are Atoms that have no specific arrangement are still considered solid matter.
    7·1 answer
  • Please help me asap thank you
    9·1 answer
  • 2- Bromo – 2 – methyl propane is :
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!