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3 years ago

What are the standard ways to make a solution of known concentration? (select all that apply.)?

Chemistry

1 answer:

MatroZZZ [7]3 years ago

8 0

1- Molar solutions: based on number of moles of chemical in 1 litre of solution

2- Weight % solution: the weight of chemical divided by the total weight of the solution (chemical + water) and multiplied by 100.

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A gas at 300 k and 4.0 atm is moved to a new loacation with a temperature of 250 k. The volume changes from 5.5 L to 2.0 L. What

alexgriva [62]

Answer is: the pressure of the gas is 9,2 atm.
p₁ = 4,0 atm.
T₁ = 300 K.
V₁ = 5,5 L.
p₂ = ?
T₂ = 250 K.
V₂ = 2,0 L.
Use combined gas law - the volume of amount of gas is proportional to the ratio of its Kelvin temperature and its pressure.
p₁V₁/T₁ = p₂V₂/T₂.
4 atm · 5,5 L ÷ 300 K = p₂ · 2,0 L ÷ 250 K.
0,0733 = 0,008p₂.
p₂ = 9,2 atm.

4 0

3 years ago

What is the mass of KOH found in a 785 mL of a 1.43 M solution of KOH

My name is Ann [436]

Molarity is defined as the ratio of number of moles to the volume of solution in litres.

The mathematical expression is given as:

$Molarity = \frac{Number of moles}{volume of solution in litres}$

Here, molarity is equal to 1.43 M and volume is equal to 785 mL.

Convert mL into L

As, 1 mL = 0.001 L

Thus, volume = $785\times 0.001$ = 0.785 L

Rearrange the formula of molarity in terms of number of moles:

$Number of moles =molarity\times volume of solution in litres$

n = $1.43 M \times 0.785 L$

= 1.12255 mole

Now, Number of moles = $\frac{mass in g}{molar mass}$

Molar mass of potassium hydroxide = 56.10 g/mol

1.12255 mole = $\frac{mass in g}{56.10 g/mol}$

mass in g = $1.12255 mole\times 56.10 g/mol$

= 62.97 g

Hence, mass of $KOH$ = 62.97 g

7 0

3 years ago

I need help ASAP!!!!!!!!!!!!!!!!!!!

liraira [26]

last one? don't take my word though

Explanation:

the suns heat is related to nuclear fusion

6 0

1 year ago

What is the mass of 4.32 mol GaI3? 455 g 1,230 g 1,720 g 1,950 g

denis23 [38]

Answer:

D. 1,950 g

Explanation:

I completed the test and it is the correct answer!

8 0

3 years ago

g A 500. mL solution contains 0.665 M NaC2H3O2 and 0.475 M HC2H3O2. What mass of HCl in grams needs to be added for the solution

77julia77 [94]

Answer:

7.38g HCl

Explanation:

Using H-H equation for acetic buffer:

pH = pKa + log [NaC2H3O2] / [HC2H3O2]

Where pKa is -log Ka = 4.74 and [] could be taken as moles of each compound.

The initial moles of each specie is:

[NaC2H3O2]:

0.500L * (0.665mol/L) = 0.3325moles

[HC2H3O2]:

0.500L * (0.475mol/L) = 0.2375 moles

That means total moles are:

[NaC2H3O2] + [HC2H3O2] = 0.57 moles (1)

And solving H-H equation for a pH of 4.21:

4.21 = 4.74 + log [NaC2H3O2] / [HC2H3O2]

0.29512 = [NaC2H3O2] / [HC2H3O2] (2)

Replacing (1) in (2):

0.29512 = 0.57mol - [HC2H3O2] / [HC2H3O2]

0.29512 [HC2H3O2] = 0.57mol - [HC2H3O2]

1.29512 [HC2H3O2] = 0.57mol

[HC2H3O2] = 0.44 moles

The HCl reacts with NaC2H3O2 producing HC2H3O2, that means you need to add:

0.44 moles - 0.2375 moles =

0.2025 moles of HCl

Using molar mass of HCl (36.45g/mol), to convert these moles to grams:

0.2025 moles * (36.45g/mol) =

8 0

2 years ago