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3 years ago

A sample of water contains 5.24x10^22 molecules. How many moles are in this sample?

Chemistry

1 answer:

Helga [31]3 years ago

8 0

Answer:

0.087 moles of water

Explanation:

Given data:

Number of molecules of water = 5.24×10²² molecules

Number of moles of water = ?

Solution:

The given problem will solve by using Avogadro number.

1 mole = 6.022 × 10²³ molecules of water

5.24×10²² molecules × 1 mol / 6.022 × 10²³ molecules

0.87×10⁻¹ mol

0.087 mol

Avogadro number:

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance. The number 6.022 × 10²³ is called Avogadro number.

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can someone explain how this is wrong? I don’t think it is wrong but my chem teacher deducted points. so why?

ruslelena [56]

Answer: measure the mass (48.425g) of KCl

Explanation:

To prepare the solution 0.65M KCl we must measure the mass of KCl that would be dissolved in 1L of the solution. This can be achieved by:

Molar Mass of KCl = 39 + 35.5 = 74.5g/mol

Number of mole (n) = 0.65

Mass conc of KCl = n x molar Mass

Mass conc of KCl = 0.65 x 74.5 = 48.425g

Therefore, to make 0.65M KCl, we must measure 48.425g

7 0

3 years ago

How many grams of AICI: are needed to produce 150 grams of NaCl?

Anettt [7]

Answer:

18.7g

Explanation:

5 0

3 years ago

What is the mass of 2.70 ×10^22 molecules of NaOH (Molar mass = 40.0 g/mol)?

Viefleur [7K]

Data:
Molar Mass of NaOH = 40 g/mol

Solving: <span>According to the Law Avogradro, we have in 1 mole of a substance, 6.02x10²³ atoms/mol or molecules
</span>
1 mol -------------------- 6.02*10²³ molecules
y mol -------------------- 2.70*10²² molecules

6.02*10²³y = 0.270*10²³
$y = \frac{0.270*\diagup\!\!\!\!\!\!10^{\diagup\!\!\!\!\!\!23}}{6.02*\diagup\!\!\!\!\!\!10^{\diagup\!\!\!\!\!\!23}}$
$\boxed{y \approx 0.04\:mol}$

Solving: <span>Find the mass value now
</span>
40 g ----------------- 1 mol of NaOH
x g ------------- 0.04 mol of NaOH

$x = 40*0.04$
$\boxed{\boxed{x = 1.6\:g}}\end{array}}\qquad\quad\checkmark$

Answer:
The mass is 1.6 grams

6 0

3 years ago

How much heat is lost when 0.440 mol of steam condenses at 100 °C?

dusya [7]

Answer:

17,890 J

Explanation:

The amount of heat released by a gaseous substance when it condenses is given by the formula

$Q=n\lambda_v$

where

n is the number of moles of the substance

$\lambda_v$ is the latent heat of vaporization

The formula can be applied if the substance is at its vaporization temperature.

In this problem, we have:

n = 0.440 mol is the number of moles of steam

$\lambda_v=40,660 J/mol$ is the latent heat of vaporization of water

And the steam is already at 100C, so we can apply the formula:

$Q=(0.440)(40660)=17,890 J$

8 0

3 years ago

a chemistry teacher adds 50.0 ml of 1.50 m h2so4 solution to 200 ml of water. What is the concentration of the final solution?

nevsk [136]

Answer:0.300M

Explanation:1) Data:

a) Initial solution

M = 1.50M

V = 50.0 ml = 0.050 l

b) Solvent added = 200 ml = 0.200 l

2) Formula:

Molarity: M = moles of solute / volume of solution is liters

3) Solution:

a) initial solution:

Clearing moles from the molarity formula: moles = M × V

moles of H₂SO₄ = M × V = 1.5M × 0.050 l = 0.075 mol

b) final solution:

i) Volumen of solution = 0.050 l + 0.200l = 0.250l

ii) M = 0.075 mol / 0.250 l = 0.300M ← answeer

5 0

3 years ago