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3 years ago

What is the freezing point of an aqueous solution that has 25.00 g of calcium iodide dissolved in 1250 g of water?

Chemistry

1 answer:

ozzi3 years ago

6 0

Answer:

- 0.380ºC

Explanation:

The lowering of the freezing point of a solvent is a colligative property ruled by the formula:

$\Delta T_f=K_f\times m\times i$

Where:

ΔTf is the lowering of the freezing point

Kf is the molal freezing constant of the solvent: 1.86 °C/m

m is the molality of the solution

i is the van't Hoff factor: the number of particles (ions) per unit of ionic compound.

a) molality, m

m = number of moles of solute/ kg of solvent

number of moles of CaI₂ = mass in grams/ molar mass

number of moles of CaI₂ = 25.00g / 293.887 g/mol = 0.0850667mol

m = 0.0850667mol/1.25 kg = 0.068053m

b) i

Each unit of CaI₂, ideally, dissociates into 1 Ca⁺ ion and 2 I⁻ ions. Thus, i = 1 + 2 = 3

c) Freezing point lowering

ΔTf = 1.86 °C/m × 0.068053m × 3 = 0.3797ºC ≈ 0.380ºC

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________ climate is summerless with the average temperature of the warmest month below 10°c.

amid [387]

Answer:

Polar

Explanation:

A polar climate is a place where the climate usually has a temperature below freezing, icy, and covered in snow. These areas do not get direct heat and sunlight from the sun. Polar climates are located at the North Pole of the Arctic, and at the South Pole on the continent of Antarctica.

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2 years ago

At a given temperature, 2.6 atm of h2 and 3.14 atm of cl2 are mixed and allowed to come to equilibrium. the equilibrium pressure

Keith_Richards [23]

The solution would be like this for this specific problem:

Given:

H2 = 2.6 atm
CL2 = 3.14 atm

pressure H2 = 2.6 - x
pressure Cl2 = 3.14 - x
pressure HBr = 2x = 1.13

x = 1.13 / 2 = 0.565

pressure H2 = 2.6 - 0.565 = 2.035
pressure Br2 = 3.14 - 0.565 = 2.575

Kp = (1.13)^2 / 2.035 x 2.575

= 1.2769 / (5.240125)

= 0.24367739319195629875241525726963

= 0.244

Therefore, the Kp for the reaction at the given temperature is 0.244.

To add, the hypothetical pressure of a gas if it alone occupied the whole volume of the original mixture at the same temperature is called the partial pressure or Kp.

7 0

3 years ago

The following diagrams represent mixtures of NO(g) and O2(g). These two substances react as follows: 2NO(g)+O2(g)→2NO2(g) It has

Alja [10]

This is an incomplete question, here is a complete question and an image is attached below.

The following diagrams represent mixtures of NO(g) and O₂(g). These two substances react as follows:

$2NO(g)+O_2(g)\rightarrow 2NO_2(g)$

It has been determined experimentally that the rate is second order in NO and first order in O₂.

Based on this fact, which of the following mixtures will have the fastest initial rate?

The mixture (1). The mixture (2). The mixture (3).

Answer : The mixture 1 has the fastest initial rate.

Explanation :

The given chemical reaction is:

$2NO(g)+O_2(g)\rightarrow 2NO_2(g)$

The rate law expression is:

$Rate=k[NO]^2[O_2]$

Now we have to determine the number of molecules of $NO\text{ and }O_2$

In mixture 1 : There are 5 $NO$ and 4 $O_2$ molecules.

In mixture 2 : There are 7 $NO$ and 2 $O_2$ molecules.

In mixture 3 : There are 3 $NO$ and 5 $O_2$ molecules.

Now we have to determine the rate law expression for mixture 1, 2 and 3.

The rate law expression for mixture 1 is:

$Rate=k[NO]^2[O_2]$

$Rate=k(5)^2\times (4)$

$Rate=k(100)$

The rate law expression for mixture 2 is:

$Rate=k[NO]^2[O_2]$

$Rate=k(7)^2\times (2)$

$Rate=k(98)$

The rate law expression for mixture 3 is:

$Rate=k[NO]^2[O_2]$

$Rate=k(3)^2\times (5)$

$Rate=k(45)$

Hence, the mixture 1 has the fastest initial rate.

4 0

3 years ago

Which of the following information is necessary to describe an object's motion?

Zepler [3.9K]

Answer: The correct option is B.

Explanation: To describe the motion of an object, we use the equations of motion.

$v=u+at$
$s=ut+\frac{1}{2}at^2$
$2as=v^2-u^2$

From the above equations, we require position, speed and direction through which we an calculate the displacement, velocity and acceleration.

To calculate the complete motion of an object, we require all the three factors.

Hence, the correct option is B.

8 0

3 years ago

Read 2 more answers

How much heat is added if .0948g of water is increased in temperature by .728 degrees C?

Verdich [7]

Answer:

0.289J of heat are added

Explanation:

We can relate the change in heat of a substance with its increasing in temperature using the equation:

q = m*ΔT*S

Where Q is change in heat

m is mass of substance (In this case, 0.0948g of water)

ΔT = 0.728°C

S is specific heat (For water, 4.184J/g°C)

Replacing:

q = 0.0948g*0.728°C*4.184J/g°C

q = 0.289J of heat are added

5 0

3 years ago