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sasho [114]
3 years ago
8

What is the molar mass of a covalent compound if 0.486 g of it is dissolved in 25.0 ml of water and produces a freezing temperat

ure of -0.40 °c?
Chemistry
1 answer:
Semmy [17]3 years ago
3 0

Answer is: the molar mass of a covalent compound is 90.4 g/mol.

<span> m(compound) = 0.486 g.
m(water) = 25 mL </span>· 1 g/mL = 25 g ÷ 1000 g/kg = 0.025 kg.<span>
ΔT = 0°C - (-0.40°C) = 0.40°C.</span>

Kf(H₂O) = 1.86°C/m.

M(compound) = Kf · m(compound<span>) / m(water) · ΔT.
M</span>(compound)<span>= 1.86°C/m · 0.486 g / (0.025 kg · 0.4°C).
M</span>(compound) = 90.4 g/mol.

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If 20 grams of N2 react completely with H2 , how many moles of NH3 are produced? Show Work
Maslowich
This is the balanced eq
N2 + 3H2 -> 2NH3
first you need to find mole of N2 by using
mol = mass ÷ molar mass.
mol N2= 20g ÷ (14.01×2)g/mol
=0.7138mol
then look at the coefficient between H2 and NH3.
it is N2:NH3
1:2
0.7138:0.7138×2
0.7138:1.4276 moles
moles of NH3 = 1.4276 moles
5 0
3 years ago
A student prepares a weak acid solution by dissolving 0.2000 g HZ to give 100. mL solution. The titration requires 33.5 mL of 0.
nexus9112 [7]

Answer:

a)M=0.20/(0.335*0.1025)= 0.20/ 0.034 = 5.88 g/mol

b) if 0.100g is used instead of 0.200g

M = 0.1 / 0.034 = 2.94  hence the molar mass will be too low

Explanation:

0.2000 gHZ gives  100ml acid solution

33.5 ml of 0.1025 M NaOH  is required to prepare it

the moles = mass / molar mass

mass = 0.200 gHZ

moles = 0.0335*100 * 0.1025 = 0.034

therefore molar mass = mass / moles

                                  M=0.20/(0.335*0.1025)= 0.20/ 0.034 = 5.88

if 0.100g is used instead of 0.200g

M = 0.1 / 0.034 = 2.94  hence the molar mass will be too low

3 0
3 years ago
How many grams of water are produced when 4.50 L of
MA_775_DIABLO [31]

The answer for the following problem has been mentioned below.

  • <em><u>Therefore the mass of the water is 5.802 grams.</u></em>

Explanation:

Given:

volume of oxygen (V) = 4.50 L

Temperature (T) = 425 K

pressure of oxygen (P) = 2.50 atm

Gram molecular mass of oxygen (M) = 16.0 grams

To calculate:

mass of water (m)

We know;

According to the ideal gas equation;

     P × V = n × R × T

As we know;

no of moles = \frac{m}{M}

m represents the mass of oxygen (m)

M represents the Gram molecular mass (M)

According to above mentioned equation;

           P × V = n × R × T

P represents the pressure of the oxygen

V represents the volume of the oxygen

n represents the no of moles of the oxygen

R represents the universal gas constant

where,

the value of R is 0.0821 L atm/K moles

Substituting the values in the above equation;

                  2.50 × 4.50 = \frac{m}{16.0} × 0.0821 × 425

                   11.25 =  \frac{m}{16.0} × 34.8925

                  180 = m × 34.8925

                  m = \frac{180}{34.8925}

                  m = 5.158 grams

Therefore the mass of the of oxygen is 5.158 grams

Now;

As we know;

           \frac{m_{1} }{M_{1} } = \frac{m_{2} }{M_{2} }

where;

m_{1} represents the mass of the oxygen

M_{1} represents the gram molecular mass of the oxygen

m_{2} represents the mass of the water

M_{2} represents the gram molecular mass of water

    From the above given formula,

      \frac{5.158}{16.0} = \frac{m_{2} }{18}

where;

Gram molecular weight of water = 18.0 u

    m_{2} = 5.802 grams

<em><u>Therefore the mass of the water is 5.802 grams.</u></em>

5 0
3 years ago
5) Calculate the molality of 0.210 mol of KBr dissolved in 0.075kg pure<br> water?
Margaret [11]

Answer:

\boxed {\boxed {\sf 2.8 \ m }}

Explanation:

The formula for molality is:

m=\frac{moles \ of \ solute}{kg \ of \ solvent}

There are 0.210 moles of KBr and 0.075 kilograms of pure water.

moles= 0.210 \ mol \\kilograms = 0.075 \ kg

Substitute the values into the formula.

m= \frac{ 0.210 \ mol }{0.075 \ kg}

Divide.

m= 2.8 \ mol/kg= 2.8 \ m

The molality is <u>2.8 moles per kilogram</u>

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The average person in the United States is exposed to the following amount of radiations annually. Rank the following source of
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<span>#1 is air radon, #2 is x-ray, #3 is ground, #4 is cosmic radiation, #5 is TV tube, #6 is weapons test fallout . That's all I got hope I helped!</span>
8 0
3 years ago
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