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
Leokris [45]
3 years ago
13

A certain substance X has a normal freezing point of 5.6 °C and a molal freezing point depression constant Kf-7.78 °C-kg·mol-1.

A solution is prepared by dissolving some urea ((NH2)2CO) in 550. g of Χ. This solution freezes at-0.9 °C. Calculate the mass of urea that was dissolved. Be sure your answer has the correct number of significant digits.
Chemistry
1 answer:
Harrizon [31]3 years ago
7 0

Answer:

27.60 g urea

Explanation:

The <em>freezing-point depression</em> is expressed by the formula:

  • ΔT= Kf * m

In this case,

  • ΔT = 5.6 - (-0.9) = 6.5 °C
  • Kf = 7.78 °C kg·mol⁻¹

m is the molality of the urea solution in X (mol urea/kg of X)

First we<u> calculate the molality</u>:

  • 6.5 °C = 7.78 °C kg·mol⁻¹ * m
  • m = 0.84 m

Now we<u> calculate the moles of ure</u>a that were dissolved:

550 g X ⇒ 550 / 1000 = 0.550 kg X

  • 0.84 m = mol Urea / 0.550 kg X
  • mol Urea = 0.46 mol

Finally we <u>calculate the mass of urea</u>, using its molecular weight:

  • 0.46 mol * 60.06 g/mol = 27.60 g urea

You might be interested in
Which of the following statements is NOT true of the Lewis Dot Diagrams?
vivado [14]
You tryna cheat? I think it’s four so hopefully not
7 0
3 years ago
Read 2 more answers
Name the following:<br> Simple chemical molecules made of single unit
Stolb23 [73]

Answer:

atom is the answer I think

7 0
3 years ago
Element A has a half-life of 10 days. A scientist measures out 200 g of this substance. After 30 days has passed, the scientist
myrzilka [38]
N=N₀*2^(-t/T)

N₀=200 g
T=10 d
t=30 d

N=200*2^(-30/10)=25 g

25 g will remain
4 0
3 years ago
Read 2 more answers
As ___ increases,___ increases
Goshia [24]

Answer:

if the force applied increases

if the area of contact increases

Explanation:

8 0
2 years ago
Which gas below has the largest number of moles at STP?
ArbitrLikvidat [17]

Answer:

a.) 22.4 L Ne.

Explanation:

It is known that every 1.0 mol of any gas occupies 22.4 L.

For the options:

  • 22.4 L Ne:

<em>It represents </em><em>1.0 mol of Ne.</em>

<em />

  • 20 L Ar:

using cross multiplication:

1.0 mol occupies → 22.4 L.

??? mol occupies → 20 L.

The no. of moles of (20 L) Ar = (1.0 mol)(20 L)/(22.4 L) = 0.8929 mol.

  • 2.24 L Xe:

using cross multiplication:

1.0 mol occupies → 22.4 L.

??? mol occupies → 2.24 L.

<em>The no. of moles of (2.24 L) Xe </em>= (1.0 mol)(2.24 L)/(22.4 L) = <em>0.1 mol.</em>

  • So, the gas that has the largest number of moles at STP is: a.) 22.4 L Ne.

6 0
3 years ago
Other questions:
  • How many moles of nh3 can be produced from 13.5 mol of h2 and excess n2?
    9·1 answer
  • During ______ the composition of a substance does not change
    10·1 answer
  • Is matter and mass always the same
    14·2 answers
  • One mole of particles of any substance contains how many particles?
    8·1 answer
  • PLEASE HELP!!!! Will give 60 points, and mark brainlest! Correct answer and explanation PLEASE!!!
    5·1 answer
  • I NEED HELP ASAP ILL GIVE 10 POINTS​
    8·1 answer
  • If you diluted 120 mL of 1,049 M NaCl to 1,920 mL, what would
    15·1 answer
  • Which BEST describes the role of mitochondiſa in maintaining homeostasis for the cell?
    14·1 answer
  • The electronic structures of atoms X and Y are shown.
    8·1 answer
  • Which layer of Earth is responsible for the movement of tectonic plates?
    5·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!