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3 years ago

How many grams of CaCl2 are need to prepare 250 mL of a 0.15M solution?

Chemistry

1 answer:

Tanzania [10]3 years ago

4 0

Answer:

Here is what I got from reading this question...

Explanation:

So if you dissolve 7.5625- g of CaCl2 in water, dissolve well and then add distilled in a 250- ml standard flask upto the mark and shake well for uniform Concentration, you will get 0.25- M CaCl2 solution.

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How much energy does an X-ray with an 8 nm (8 x 10-9 m) wavelength have?

Vlada [557]

Answer: 2.48×10^-17 J

Explanation:

Given the following :

Wavelength = 8nm (8 x 10^-9 m)

Energy(e) of X-ray =?

Energy=[speed of light(c) × planck's constant (h)] ÷ wavelength

Speed of light = 3×10^8m/s

Planck's constant = 6.626×10^-34 Js

Wavelength = 8 x 10^-9 m

Energy = [(3×10^8) * (6.626×10^-34)] / 8 x 10^-9

Energy = [19.878×10^(8-34)] / 8 x 10^-9

Energy = 2.48475 × 10^(-26+9)

Energy = 2.48×10^-17 J

8 0

2 years ago

How many moles are found in 10.5 g of Pb?

deff fn [24]

Answer:

Number of moles = 0.05 mol

Explanation:

Given data:

Mass of Pb = 10.5 g

Number of moles of Pb = ?

Solution:

Formula:

Number of moles = mass/molar mass

Molar mass of Pb is 207.2 g/mol.

Now we will put the values in formula.

Number of moles = 10.5 g/207.2 g/mol

Number of moles = 0.05 mol

6 0

2 years ago

A 7.0 g sample of a hydrocarbon (a molecule that has only hydrogen and carbon) is subject to combustion analysis. The mass of CO

Akimi4 [234]

Answer: The empirical formula for the given compound is $CH_2$

Explanation:

The chemical equation for the combustion of compound having carbon and hydrogen follows:

$C_xH_y+O_2\rightarrow CO_2+H_2O$

where, 'x' and 'y' are the subscripts of carbon and hydrogen respectively.

We are given:

Mass of $CO_2=22.0g$

We know that:

Molar mass of carbon dioxide = 44 g/mol

For calculating the mass of carbon:

In 44 g of carbon dioxide, 12 g of carbon is contained.

So, in 22.0 g of carbon dioxide, $\frac{12}{44}\times 22.0=6g$ of carbon will be contained.

For calculating the mass of hydrogen:

Mass of hydrogen = Mass of sample - Mass of carbon

Mass of hydrogen = 7.0 g - 6 g

Mass of hydrogen = 1.0 g

To formulate the empirical formula, we need to follow some steps:

Step 1: Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{6g}{12g/mole}=0.5moles$

Moles of Hydrogen = $\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{1.0g}{1g/mole}=1.0moles$

Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.5 moles.

For Carbon = $\frac{0.5}{0.5}=1$

For Hydrogen = $\frac{1.0}{0.5}=2$

Step 3: Taking the mole ratio as their subscripts.

The ratio of Fe : C : H = 1 : 2

Hence, the empirical formula for the given compound is $C_{1}H_{2}=CH_2$

4 0

3 years ago

Please help 21 points

Novosadov [1.4K]

Answer:

You

Explanation:

Will have to fill in the graph organizer with a story

4 0

2 years ago

Which pH value represents a solution with the lowest OHM<br> ion concentration?

Arlecino [84]

pH value 1 represents a solution with the lowest OH⁻ion concentration.

<u>Explanation:</u>

pH is given by the expression as the negative logarithm to the base 10 of the concentration of hydrogen ions.

pH = -log₁₀[H⁺]

If the pH is lower than 7, pH < 7 then it is acidic

If the pH = 7, then it is neutral

If the pH > 7, then it is basic

If pH is 1 then the solution is showing mostly acidic character,which is least basic in its character.

So if the pH is 1, which is most acidic and least basic solution that is lowest OH⁻ ion concentration.

7 0

3 years ago