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3 years ago

What is the molality (m) of a solution that contains 76.5 g of KCl dissolved in 85.0 g of water?

Chemistry

1 answer:

ladessa [460]3 years ago

5 0

Answer:

76.5g KCl/74.55 grams per mole Kcl = x

molality= x/.085 kg H2O

Explanation:

well remember molality is moles of solute/kilograms of solvent. So it's the moles of KCl over 85 g of h20 converted into kg. if this makes sense.

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Volume is an extensive physical property because it is dependent on the size of the sample.

BaLLatris [955]

Hi,

The statement is true, as the volume of a sample depends on its size.

I hope this helps. If I was not clear enough or if you’d like further explanation please let me know. Also, English is not my first language, so I’m sorry for any mistakes.

7 0

3 years ago

Read 2 more answers

HELP DUE MONDAY!! Don’t understand

Katyanochek1 [597]

Answer:

Concept: Chemical Analysis

You need to start by graphing the data and then analyzing it.
We can see that the horse has a distance in meters of 980 at the end of the 10 seconds hence it is the fastest.
The horse line has a linearly representation, while the alternate line has parabolic tendencies towards the end. The steeper line indicates a faster change in time or velocity which results in a greater distance traveled indicating that the horse is faster.
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5 0

3 years ago

How many moles of glucose are in 19.1g of glucose?

Crank

Answer:

0.106 mol (3s.f.)

Explanation:

To find the number of moles, divide the mass of glucose (in grams) by its Mr. Glucose has a chemical formula of C6H12O6. To find the Mr, add all the Ar of all the atoms in C6H12O6.

Ar of C= 12, Ar of H= 1, Mr of O= 16

These Ar values can be found on the periodic table.

Mr of glucose= 6(12)+ 12(1) + 6(16)= 180

Moles of glucose

= mass ÷ mr

= 19.1 ÷ 180

= 0.106 mol (3 s.f.)

3 0

3 years ago

Sighting along the C2-C3 bond of 2-methylbutane, the least stable conformation (Newman projection) has a total energy strain of

natima [27]

Answer:

21 KJ/mol

Explanation:

For this question, we have to start with the linear structure of 2-methylbutane. With the linear structure, we can start to propose all the Newman projections keep it in mind that the point of view is between carbons 2 and 3 (see figure 1).

Additionally, we have several energy values for each interaction present in the Newman structures:

-) Methyl-methyl gauche: 3.8 KJ/mol

-) Methyl-H eclipse: 6.0 KJ/mol

-) Methyl-methyl eclipse: 11.0 KJ/mol

-) H-H eclipse: 4.0 KJ/mol

Now, we can calculate the energy for each molecule.

Molecule A

In this molecule, we have 2 Methyl-methyl gauche interactions only, so:

(3.8x2) = 7.6 KJ/mol

Molecule B

In this molecule, we have a Methyl-methyl eclipse interaction a Methyl-H eclipse interaction and an H-H eclipse interaction, so:

(11)+(6)+(4) = 21 KJ/mol

Molecule C

In this molecule, we have 1 Methyl-methyl gauche interaction only, so:

3.8 KJ/mol

Molecule D

In this molecule, we have three Methyl-H eclipse interaction, so:

(6*3) = 18 KJ/mol

Molecule E

In this molecule, we have 1 Methyl-methyl gauche interaction only, so:

3.8 KJ/mol

Molecule F

In this molecule, we have a Methyl-methyl eclipse interaction a Methyl-H eclipse interaction and an H-H eclipse interaction, so:

(11)+(6)+(4) = 21 KJ/mol

The structures with higher energies would be less stable. In this case, structures B and F with an energy value of 21 KJ/mol (see figure 2).

I hope it helps!

3 0

3 years ago

A gaseous system undergoes a change in temperature and volume. What is the entropy change for a particle in this system if the f

viva [34]

Answer: -2.373 x 10^-24J/K(particles

Explanation: Entropy is defined as the degree of randomness of a system which is a function of the state of a system and depends on the number of the random microstates present.

The entropy change for a particle in a system depends on the initial and final states of a system and is given by Boltzmann equation as

S = k ln(W) .

where S =Entropy

K IS Boltzmann constant ==1.38 x 10 ^-23J/K

W is the number of microstates available to the system.

The change in entropy is given as

S2 -S1 = kln W2 - klnW1

dS = k ln (W2/W1)

where w1 and w2 are initial and final microstates

from the question, W2(final) = 0.842 x W1(initial), so:

= 1.38*10-23 ln (0.842)

=1.38*10-23 x -0.1719

= -2.373 x 10^-24J/K(particles)

4 0

3 years ago