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
REY [17]
3 years ago
6

A salt is known to be an alkali metal fluoride. A quick approximate determination of freezing point indicates that 4 g of the sa

lt dissolved in 100 g of water produces a solution that freezes at about −1.4 °C. What is the formula of the salt? Show your calculations.
Chemistry
2 answers:
iVinArrow [24]3 years ago
6 0

Answer: RbF

Explanation:

Depression in freezing point is given by:

\Delta T_f=i\times K_f\times m

\Delta T_f=T_f^0-T_f=(0-(-1.4)^0C=1.4^0C = Depression in freezing point

i= vant hoff factor = 2 (for alkali metal flouride, MF)

K_f = freezing point constant = 1.86^0C/m

m= molality

\Delta T_f=i\times K_f\times \frac{\text{mass of solute}}{\text{molar mass of solute}\times \text{weight of solvent in kg}}

Weight of solvent (water)= 100 g = 0.1 kg  

Molar mass of unknown solute = ? g/mol

Mass of unknown solute added = 4 g

1.4=2\times 1.86\times \frac{4g}{M g/mol\times 0.1kg}

M=106g/mol

Thus the mass of MF is 106 g/mol

x + 19 = 106

x = 87 g

Thus the atomic mass is near to that of rubidium, thus the formula of the salt is RbF

nexus9112 [7]3 years ago
4 0
For the answer to the question above, I can't help you directly because I don't have a calculator right now. But I'll show you how to solve this.
<span>use the freezing point depression formula for this one: delta T = i * m * K where K is a constant, m is the molality (mol solute/kg solvent), and i is the van'hoff factor the van hoff factor is the number of ions that your salt dissociates into. Since it's an ALKALI flouride salt, how many ions? k is just a constant, you get it from a table in your textbook somewhere So you have everything to solve for the molality of the solution, once you did that, multiplying it by the mass of water to find the mols of the salt. Take the mass of the salt and divide by this mols to figure out the molar mass, and then compare it with the periodic table to identify the salt.
</span>
<u>Mole solute</u>   x  mass of Water  = Mol solute<u>
</u>kg Solvent

then 

Mass of solute  x  <u>            1             </u>   =  molar mass
                               mole of solute

You might be interested in
Describe how you could use two LB/agar plates, some E. coli, and some ampicillin to determine how E. coli cells are affected by
KiRa [710]

Answer:

For this experiment we are going to take plate 1 as the control plate, so, in it there will be just E. coli in LB/agar; in plate 2, we are going to put E. coli in LB/agar and some ampicillin.  Then, we have to wait for the E. coli colonies to form. After a while, the E. coli growth can be compared on both plates and determine if ampicillin affects or not the E. coli colonies.

Explanation:

If the ampicillin affects negatively E. coli colonies, we are going to observe that in plate 1 (control plate) there are E. coli colonies growing, but in plate 2, there is no E. coli colonies or, at least, there is a fewer number of colonies on it. If ampicillin doesn't affect E.coli, plate 1 (control) and plate 2 (ampicillin experiment) are going to be similar in number of colonies.

8 0
3 years ago
I dont understand this question can u guys help
diamong [38]

Answer: B

bye

Explanation:

6 0
2 years ago
Read 2 more answers
Keq for the reaction below is 2400. If the initial conditions of the reaction are a 1.0 L flask that contains 0.024 mol NO (g),
podryga [215]

Answer:

The answer to your question is it is not at equilibrium, it will move to the products.

Explanation:

Data

Keq = 2400

Volume = 1 L

moles of NO = 0.024

moles of N₂ = 2

moles of O₂ = 2.6

Process

1.- Determine the concentration of reactants and products

[NO] = 0.024 / 1 = 0.024

[N₂] = 2/1 = 2

[O₂] = 2.6/ 1= 2.6

2.- Balanced chemical reaction

                     N₂ + O₂    ⇒   2NO

3.- Write the equation for the equilibrium of this reaction

                     Keq = [NO]²/[N₂][O₂]

- Substitution

                    Keq = [0.024]² / [2][2.6]

-Simplification

                    Keq = 0.000576 / 5.2

-Result

                    Keq = 1.11 x 10⁻⁴

Conclusion

It is not at equilibrium, it will move to the products because the experimental Keq was lower than the Keq theoretical-

                         1.11 x 10⁻⁴ < 2400

7 0
3 years ago
What happend to the pressure of a gas inside a container if the temperatures of the gas decreases
ludmilkaskok [199]
There is an increase in the number of collisions between particles and the walls of the container<span>. b. There is an increase in the </span>temperature of the gas. If<span> the volume of a </span>container<span> of </span>gas<span> is reduced, what will </span>happen to the pressure inside<span> the </span>container
4 0
3 years ago
HI HELP ONLY DO THE 2nd ONE!
Likurg_2 [28]
I would say they design and build things.
8 0
2 years ago
Read 2 more answers
Other questions:
  • The solid form of a substance is usually more dense than its liquid and gaseous forms. Similarly the liquid form is usually more
    11·1 answer
  • Which of the following only takes into account distance and time? Question 18 options: displacement velocity speed acceleration
    12·1 answer
  • I don't know how to solve no 5 <br> And i really need it fast and in french
    11·1 answer
  • A solution is made by dissolving 10.20 grams of glucose (C6H12O6) in 355 grams of water. What is the freezing point depression o
    9·1 answer
  • Calculate the mass volume percent of a NaCl solution in which 186 g of NaCl is dissolved in enough water to give a total volume
    14·1 answer
  • An ionic bond involves the.....
    14·2 answers
  • Which of the following statements best describes why electrons
    5·1 answer
  • You have 5 cars and you double that amount.How much cars do you have.
    7·1 answer
  • A solution of 1.8274g of a polypeptide in 274mL of a aqueous solution has an osmotic pressure at 31.40 degrees C of 2.012 mmHg.
    6·1 answer
  • An 80 ev electron impinges upon a potential barrier 100 ev high and 0. 2 nm thick. what is the probability the electron will tun
    8·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!