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3 years ago

What is the percent by mass of 54.7g of calcium chloride dissolved in 500g of water?

1 answer:

3 0

% by mass = (mass solute/mass solution)*100%
mass of the solute = 54.7 g
mass of the solution = mass solute + mass solvent=54.7+500=554.7 g
% by mass = (54.7/554.7)*100%≈0.0986*100% = 9.86%

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A 50.0 mL solution of 0.141 M KOH is titrated with 0.282 M HCl . Calculate the pH of the solution after the addition of each of

Kobotan [32]

Answer:

pH =1 2.84

Explanation:

First we have to start with the <u>reaction</u> between HCl and KOH:

$HCl~+~KOH->~H_2O~+~KCl$

Now <u>for example, we can use a volume of 10 mL of HCl</u>. So, we can calculate the moles using the <u>molarity equation</u>:

$M=\frac{mol}{L}$

We know that $10mL=0.01L$ and we have the concentration of the HCl $0.282M$ , when we plug the values into the equation we got:

$0.282M=\frac{mol}{0.01L}$

$mol=0.282*0.01$

$mol=0.00282$

We can do the same for the KOH values ( $50mL=0.05L$ and $0.141M$ ).

$0.141M=\frac{mol}{0.05L}$

$mol=0.141*0.05$

$mol=0.00705$

So, we have so far <u>0.00282 mol of HCl</u> and <u>0.00705 mol of KOH</u>. If we check the reaction we have a <u>molar ratio 1:1</u>, therefore if we have 0.00282 mol of HCl we will need 0.00282 mol of KOH, so we will have an <u>excess of KOH</u>. This excess can be calculated if we <u>substract</u> the amount of moles:

$0.00705-0.00282=0.00423mol~of~KOH$

Now, if we want to calculate the pH value we will need a <u>concentration</u>, in this case KOH is in excess, so we have to calculate the <u>concentration of KOH</u>. For this, we already have the moles of KOH that remains left, now we need the <u>total volume</u>:

$Total~volume=50mL+10mL=60mL$

$60mL=0.06L$

Now we can calculate the concentration:

$M=\frac{0.00423mol}{0.06L}$

$M=0.0705$

Now, we can <u>calculate the pOH</u> (to calculate the pH), so:

$pOH=-Log(0.0705)$

$pOH=1.15$

Now we can <u>calculate the pH value</u>:

$14=~pH~+~pOH$

$pH=14-1.15=12.84$

8 0

3 years ago

In the laboratory you dissolve 19.4 g of potassium acetate in a volumetric flask and add water to a total volume of 125 mL. What

aleksandrvk [35]

The molarity of the potassium acetate solution given the data is 1.584 M

<h3>What is molarity? </h3>

This is defined as the mole of solute per unit litre of solution. Mathematically, it can be expressed as:

Molarity = mole / Volume

<h3>How to determine the mole of CH₃COOK</h3>

Mass of CH₃COOK = 19.4 g
Molar mass of CH₃COOK = 98 g/mol
Mole of CH₃COOK =?

Mole = mass / molar mass

Mole of CH₃COOK = 19.4 / 98

Mole of CH₃COOK = 0.198 mole

<h3>How to determine the molarity of CH₃COOK</h3>

Mole of CH₃COOK = 0.198 mole
Volume = 125 mL = 125 / 1000 = 0.125 L
Molarity of CH₃COOK = ?

Molarity = mole / Volume

Molarity of CH₃COOK = 0.198 / 0.125

Molarity of CH₃COOK = 1.584 M

Learn more about molarity:

brainly.com/question/15370276

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Collagen in the human body connects and supports bodily tissue such as skin, bones, muscles and cartilage. It supports the internal organs and can even be found in teeth! Collagen's main function is to sustain tendons, skin, and cartilage and provide firmness and elasticity to those structures.

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