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dezoksy [38]
4 years ago
14

A mass of 100.0 g of solute is dissolved in water so that 850. mL of a 0.7500 M solution has been prepared. What is the molar ma

ss of the solute?
Chemistry
1 answer:
zmey [24]4 years ago
8 0

Answer:

156.86 g / mol

Explanation:

We start from the molarity law  

Cm = n / V

n = w / M

then

Cm = (w / M) / V

Cm = w / (M × V)

where:

Cm is the molarity  

n number of moles

w a mass of the solute  

M is the molar mass of the solute (which is needed)

V the volume of the solution in liters

Then the M can be calculated as following:  

M = w / (Cm × V)

M = 100 / (0.75 × 0.85) = 156.86 g / mol

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Calculate the ph of a solution at 25. 0 °C that contains 2. 95 × 10^-12 m hydronium ions.
Makovka662 [10]

The pH of a solution at 25. 0 °C that contains 2. 95 × 10^-12 m hydronium ions is 13.5.

<h3>What is pH? </h3>

pH is defined as the concentration of the hydrogen bond which is released or gained by the species in the solution which depicts the acidity and basicity of the solution.

<h3>What is pOH? </h3>

pOH is defined as the concentration of the hydronium ion present in solution.

pOH value is inversely proportional to the value of pH.

pH value increases, pOH value decreases and vice versa.

Given,

Total H+ ions = 2.95 ×10^(-12)M

<h3>Calculation of pH</h3>

pH = -log[H+]

By substituting the value of H+ ion in given equation

= log(2.95× 10^(-12) )

= 13.5

Thus we find that the pH of a solution at 25. 0 °C that contains 2. 95 × 10^-12 m hydronium ions is 13.5.

learn more about pH:

brainly.com/question/12942138

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8 0
2 years ago
The radioactive decay of a certain sample produced 846 disintegrations per minute. exactly 3.00 days later, the rate of decay wa
Margarita [4]

Answer:

\boxed{\text{1.81 da}}

Explanation:

1. Calculate the decay constant

The integrated rate law for radioactive decay is 1

\ln\dfrac{A_{0}}{A_{t}} = kt

where

A₀ and A_t are the counts at t = 0 and t

k is the radioactive decay constant

\ln \dfrac{846}{269} = k \times 3.00\\\\\ln3.145 = 3.00k\\1.146 = 3.00k\\\\k =\dfrac{1.146}{3}\\\\k = \text{0.382 /da}\\

2. Calculate the half-life

t_{\frac{1}{2}} = \dfrac{\ln2}{k} = \dfrac{\ln2}{0.382} = \text{1.81 da}

The half-life for decay is \boxed{\textbf{1.81 da}}.

3 0
3 years ago
What is a characteristic that can be observed or measured without changing the chemical makeup of a substance? *
olga55 [171]
The correct answer is B
4 0
3 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
3 years ago
Bacteria are very small *<br><br> True<br> False
elena-14-01-66 [18.8K]

Of course they are small

Explanation:

The only way you can see them is by a microscope or a lens and can be anywhere.

8 0
3 years ago
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