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
Ainat [17]
3 years ago
12

A certain substance X has a normal boiling point of 117.8°C and a molal boiling point elevation constant =Kb·0.63°C·kgmol−1. A s

olution is prepared by dissolving some urea NH22CO in 900.g of X. This solution boils at 118.3°C. Calculate the mass of urea that was dissolved. Round your answer to 1 significant digit.
Chemistry
1 answer:
OlgaM077 [116]3 years ago
5 0

Answer:

42.8 g was the mass of dissolved urea.

Explanation:

Boiling point elevation to solve this:

ΔT = Kb . m

where ΔT → Boiling T° of solution - Boiling T° of pure solvent

Let's replace the data given:

118.3°C - 117.8°C = 0.63°C/m . m

0.5°C / 0.63 m/°C = m → 0.793 mol/kg

Mass of solvent → 900 g → g to kg → 900 g . 1kg/1000 = 0.9 kg

Molality . kg = moles → 0.793 mol/kg . 0.9 kg = 0.714 mol

These are the moles of urea we used. Let's determine the mass dissolved.

0.714 mol . 60 g /1mol = 42.8 g

You might be interested in
Please help need a 100
Triss [41]

B directly; inversely

Pressure and volume have an inverse relationship (when one increases the other increases) while volume and temperature are direct (if one increases so does the other)

Note: these relationships are only true if other factors are constant such as the temperature, and amount (in moles).

3 0
4 years ago
What are families 3-12 on the periodic table called
fredd [130]

Answer:

transition elements

Explanation:

6 0
3 years ago
Read 2 more answers
A 40 g gold coin is cooled from 50°C to 10°C (CAu is 0.13 J/g-°
Debora [2.8K]
When the Heat gain or lose = the mass * specific heat * ΔT

and when we have the mass of gold coin= 40 g 

and the specific Heat of gold=  0.13 J/g°

and ΔT = (Tf- Ti) = 10°C - 50°C = -40 °C

so by substitution:

∴Heat H = 40 g * 0.13 J/g° * -40
               = - 208 J
4 0
3 years ago
The model below shows an atom of an element. 10 light gray and 8 dark gray balls sit at the center with 2 concentric black rings
MA_775_DIABLO [31]

Answer:

The Atomic Number of the atom of an element whose model is given is "8" that is option no. 'C' in the question.

Explanation:

An Atom comprises of 3 basic structures that are Protons, Neutrons and Electrons. The central part is the Nucleus which contains protons and neutrons having positive charge and no charge respectively. The electrons are revolving around the nucleus in electronic shells having the negative charge.

<u><em>ATOMIC NUMBER: </em></u>

Atomic number is the number of protons present inside the nucleus of an atom and it determines the place of that particular atom in the <u>Periodic Table.</u>

In the model, given in the question, the nucleus contains 2 types of balls dark gray colored and light gray colored. The key at the bottom shows the dark gray colored ball as having a positive charge and thus it represents the atomic number for the given atom of element which is <u><em>EIGHT (8).</em></u>

So, the atomic number for the given atom is 8 which is element OXYGEN.  

9 0
3 years ago
Read 2 more answers
Which reactant will be the best reactant for a nucleophilic aromatic substitution?
tangare [24]

The reactant that will be the best reactant for a nucleophilic aromatic substitution is NO₂- NO₂. The correct option is b.

<h3>What is nucleophilic aromatic substitution?</h3>

Nucleophilic aromatic substitution is a substitution process of nucleophile substance is substituted by halides in an aromatic ring. Aromatic compounds contain this type of substitution.

In option b, the compound is the one nitroxide group substituted by halogen, that is fluorine. The fluorine group is substituted in these given aromatic compounds.

Thus, the correct option is b, NO₂- NO₂.

To learn more about nucleophilic aromatic substitution, refer to the link:

brainly.com/question/28265482

#SPJ4

The question is incomplete. Your most probably complete question is given below:

NO₂F

NO₂- NO₂-F

CH₃-O

CH₃-O-F

4 0
2 years ago
Other questions:
  • Write a net ionic equation to show that quinoline, c9h7n, behaves as a bronsted-lowry base in water.
    11·1 answer
  • Calculate the net change in enthalpy for the formation of one mole of acrylic acid from calcium carbide, water and carbon dioxid
    11·1 answer
  • How many moles are in 1x10^9 molecules O2
    9·2 answers
  • What is the wavelength frequency and energy of a wavelength of 580
    8·1 answer
  • i have a crossword thing that i got from school and one of the clues is: If there are two equal and opposite forces on something
    11·2 answers
  • A 56.3-g sample of water was heated to 51.2 degrees C and added to 45.8 g of 20.3 degrees C of water in a calorimeter. Assume th
    14·1 answer
  • How many milliliters of 2.00 M H2SO4 will react with 28.0 g of NaOH?
    12·1 answer
  • Please help ! its urgent!!
    9·1 answer
  • Using equations so that aluminium oxide is amphoteric ​
    14·1 answer
  • What is an example of force pair​
    14·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!