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2 years ago

How many moles are in 36.0g. of H2O?

Chemistry

2 answers:

vampirchik [111]2 years ago

8 0

Answer:

2.0 moles

Explanation:

The relationship between the number of moles of a given substance present in a sample and the mass of the sample is given by the molar mass of the substance.

For any chemical species, you have

molar mass

the mass of exactly 1 mole

water has a molar mass of

18.015 g mol

−

which means that

mole of water has a mass of

18.015 g

18.015 g mol

−

18.015 g

1 mole H

So for every

18.015 g

of water present in your sample, you have

mole of water.

This means that your

36-g

sample will contain

⋅

given by the molar mass of H



1 mole H

18.015

2.0 moles H

~~~

The answer must be rounded to two sig figs, the number of sig figs you have for the mass of water.

Explanation:

vazorg [7]2 years ago

5 0

Answer: 2 Moles

Explanation: Moles = Mass of chemical in grams (in this case 36.0g) ➗ Relative Atomic Mass of chemical (H2O = 18)

36 ➗ 18 = 2

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Cyclohexane has a freezing point of 6.50 ∘C and a Kf of 20.0 ∘C/m. What is the freezing point of a solution made by dissolving 0

ExtremeBDS [4]

Answer:

The freezing point will be $2.9^{0}C$

Explanation:

The depression in freezing point is a colligative property.

It is related to molality as:

$Depressioninfreezing point=K_{f}Xmolality$

Where

Kf= $20\frac{^{0}C}{m}$

the molality is calculated as:

$molality=\frac{moles_{solute}}{mass_{solvent}}$

$moles=\frac{mass}{molarmass}=\frac{0.694}{154}=0.0045mol$

$massofcyclohexane=25g=0.025Kg$

$molarity=\frac{0.0045}{0.025}=0.18m$

Depression in freezing point = $20X0.18=3.6^{0}C$

The new freezing point = $6.5^{0}C-3.6^{0}C=2.9^{0}C$

5 0

2 years ago

g When 2.50 g of methane (CH4) burns in oxygen, 125 kJ of heat is produced. What is the enthalpy of combustion (in kJ) per mole

Anna [14]

Answer:

-800 kJ/mol

Explanation:

To solve the problem, we have to express the enthalpy of combustion (ΔHc) in kJ per mole (kJ/mol).

First, we have to calculate the moles of methane (CH₄) there are in 2.50 g of substance. For this, we divide the mass into the molecular weight Mw) of CH₄:

Mw(CH₄) = 12 g/mol C + (1 g/mol H x 4) = 16 g/mol

moles CH₄ = mass CH₄/Mw(CH₄)= 2.50 g/(16 g/mol) = 0.15625 mol CH₄

Now, we divide the heat released into the moles of CH₄ to obtain the enthalpy per mole of CH₄:

ΔHc = heat/mol CH₄ = 125 kJ/(0.15625 mol) = 800 kJ/mol

Therefore, the enthalpy of combustion of methane is -800 kJ/mol (the minus sign indicated that the heat is released).

3 0

2 years ago

When a 1.00 L sample of water from the surface of the Dead Sea (which is more than 400 meters below sea level and much saltier t

Harlamova29_29 [7]

Answer: Molarity of $MgCl_2$ in the original sample was 1.96M

Explanation:

Molarity is defined as the number of moles of solute dissolved per liter of the solution.

$Molarity=\frac{\text{no of moles}}{\text{Volume in L}}$

${\text {moles of solute}=\frac{\text {given mass}}{\text {molar mass}}=\frac{186g}{95g/mol}=1.96$

Now put all the given values in the formula of molarity, we get

$Molarity=\frac{1.96}{1.00L}$

$Molarity=1.96mol/L$

Thus molarity of $MgCl_2$ in the original sample was 1.96M

4 0

2 years ago

A student is given a sample of a blue copper sulfate hydrate. He weighs the sample in a dry covered porcelain crucible and got a

Nata [24]

Answer:

There are present 5,5668 moles of water per mole of CuSO₄.

Explanation:

The mass of CuSO₄ anhydrous is:

23,403g - 22,652g = 0,751g.

mass of crucible+lid+CuSO₄ - mass of crucible+lid

As molar mass of CuSO₄ is 159,609g/mol. The moles are:

0,751g × $\frac{1mol}{159,609g}$ = 4,7052x10⁻³ moles CuSO₄

Now, the mass of water present in the initial sample is:

23,875g - 0,751g - 22,652g = 0,472g.

mass of crucible+lid+CuSO₄hydrate - CuSO₄ - mass of crucible+lid

As molar mass of H₂O is 18,02g/mol. The moles are:

0,472g × $\frac{1mol}{18,02g}$ = 2,6193x10⁻² moles H₂O

The ratio of moles H₂O:CuSO₄ is:

2,6193x10⁻² moles H₂O / 4,7052x10⁻³ moles CuSO₄ = 5,5668

That means that you have <em>5,5668 moles of water per mole of CuSO₄.</em>

I hope it helps!

5 0

2 years ago

The molar concentration of a sugar solution in an open beaker has been determined to be 0.3M. Calculate the solute potential at

antoniya [11.8K]

Answer:

- 7.48

Explanation:

Given:

Concentration of the sugar solution, C = 0.3 M

Temperature, T = 27° C = 273 + 27 = 300 K

Now,

The solute potential is given as:

solute potential = - iCRT

where,

i is the number of particles the particular molecule will make in water

i = 1 for sugar

R is the universal gas constant = 0.0831 liter bar/mole-K

on substituting the respective values, we get

solute potential = - 1 × 0.3 × 0.0831 × 300

The solute potential = - 7.479 ≈ - 7.48

8 0

2 years ago