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3 years ago

1 point

Chemistry

1 answer:

Aleks04 [339]3 years ago

5 0

Answer:

Option D

Explanation:

A double displacement reaction is a type of reaction in which two reactants exchange ions to form two new compounds.

CaBr2 + 2NaOH → Ca(OH)2 + 2NaBr

Calcium Bromide + Sodium Hydroxide = Portlandite + Sodium Bromide

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The Tacoma narrows bridge collapsed due to?

vovangra [49]

Explanation: aeroflastic flutter

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3 years ago

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Calculate the number of grams of sodium chloride in the solution. (Hint: Remember that sodium chloride is a strong electrolyte.)

creativ13 [48]

The question is incomplete, here is the complete question:

A solution contains 0.115 mol $H_2O$ and an unknown number of moles of sodium chloride. The vapor pressure of the solution at 30°C is 25.7 torr. The vapor pressure of pure water at this temperature is 31.8 torr. Calculate the number of grams of sodium chloride in the solution. (Hint: Remember that sodium chloride is a strong electrolyte.)

Answer: The mass of sodium chloride in the solution is 0.714 grams

Explanation:

The formula for relative lowering of vapor pressure will be:

$\frac{p^o-p_s}{p^o}=i\times \chi_{\text{solute}}$

where,

$p^o$ = vapor pressure of solvent (water) = 31.8 torr

$p^s$ = vapor pressure of the solution = 25.7 torr

i = Van't Hoff factor = 2

$\chi_{\text{solute}}$ = mole fraction of solute (sodium chloride) = ?

Putting values in above equation, we get:

$\frac{31.8-25.7}{31.8}=2\times \chi_{NaCl}\\\\\chi_{NaCl}=0.0959$

Mole fraction of a substance is calculated by using the equation:

$\chi_A=\frac{n_A}{n_A+n_B}$

$\chi_{\text{NaCl}}=\frac{n_{\text{NaCl}}}{n_{\text{NaCl}}+n_{\text{water}}}$

We are given:

Moles of water = 0.115 moles

$0.0959=\frac{n_{\text{NaCl}}}{n_{\text{NaCl}}+0.115}\\\\n_{\text{NaCl}}=0.0122mol$

To calculate the mass for given number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Moles of NaCl = 0.0122 moles

Molar mass of NaCl = 58.5 g/mol

Putting values in above equation, we get:

$0.0122mol=\frac{\text{Mass of NaCl}}{58.5g/mol}\\\\\text{Mass of NaCl}(0.0122mol\times 58.5g/mol)=0.714g$

Hence, the mass of sodium chloride in the solution is 0.714 grams

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3 years ago

What is the freezing point in °C) of a 0.743 m

lesantik [10]

Answer:

-0.276 Degrees C

Explanation:

kf of water is 1.86

Freezing point depression= m x kf x i

i= ions present ( K+ Cl-) 1=2

1.86x2X.743= .276

Since its freezinf point depression the freezing point will lower

0-.276= -.276

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2 years ago

A material has a density of 8.9 g/cm^3. You have 3 grams of the substance. How much space does it take up? a. 0.3cm3 b. 3.0 cm3

My name is Ann [436]

D = m/ V

8.9 = 3 / V

V = 3 / 8.9

V = 0.3 cm³

Answer A

hope this helps!

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3 years ago

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A gas with a volume of 8 L at a temperature of 473K is switched to a new container with a temperature of 350K. If the pressure r

Digiron [165]

Answer:

The new volume is 5.92 L, which is approximately 6 L

Explanation:

As the gas temperature increases, the molecules move faster and take less time to reach the walls of the container. This means that the number of crashes per unit of time will be greater. That is, there will be an increase (for an instant) in the pressure inside the container and the volume will increase.

So Charles's Law is one of the gas laws that relates the volume and temperature of a certain amount of gas at constant pressure and says that: