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2 years ago

When the color changes is it a chemical change or a physical change

Chemistry

1 answer:

aev [14]2 years ago

5 0

physical

It can be chemical but it's usually physical as the molecular structure doesn't change

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What solutions do we need to work on to get accurate results?<br> A) concentrated<br> B) diluted

Bess [88]

Answer:

A

I hope this helps you!!!

7 0

3 years ago

If 27.0 mL of Ca(OH)2 with an unknown concentration is neutralized by 32.40 mL of 0.185 M HCl, what is the concentration of the

zhannawk [14.2K]

Given information : Volume of HCl = 32.40 mL

$32.40 mL\times \frac{1 L}{1000 mL}$

Volume of HCl = 0.0324 L

Concentration of HCl = 0.185 M or 0.185 mol/L (M = mol/L)

Volume of Ca(OH)2 = 27.0 mL

$27.0 mL\times \frac{1 L}{1000 mL}$

Volume of Ca(OH)2 = 0.027 L

We need to find the concentration of Ca(OH)2.

To find the concentration of Ca(OH)2 we need moles and volume of Ca(OH)2.

$Concentration (Molarity) = \frac{(Moles of Ca(OH)2)}{(Volume of Ca(OH)2)}$

Moles of Ca(OH)2 can be calculated using stoichiometry and volume of Ca(OH)2 is already given to us.

Step 1 : Find the moles of HCl using its given volume and concentration.

$Moles = Concentration \times Volume in L$

$Moles = 0.185\frac{mol}{1L}\times 0.0324 L$

Moles of HCl = 0.005994 mol HCl

Step 2 : We need to find moles of Ca(OH)2 using mol of HCl with the help of mole ratio.

Mole ratio are the coefficient present in front of the compound in a balanced equation.

Mole ratio of Ca(OH)2 : HCl = 1:2 ( 1 coefficient of Ca(OH)2 and 2 coefficient of HCl)

$(0.005994 mol HCl)\times \frac{(1 mol Ca(OH)2)}{(2 mol HCl)}$

Moles of Ca(OH)2 = 0.002997 mol Ca(OH)2

Step 3 : Find the concentration of Ca(OH)2 using its moles and volume.

$Concentration (Molarity) = \frac{(Moles of Ca(OH)2)}{(Volume of Ca(OH)2)}$

Moles of Ca(OH)2 = 0.002997 mol and volume of Ca(OH)2 = 0.027 L

$Concentration (Molarity) = \frac{(0.002997 mol)}{(0.027 L)}$

Concentration of Ca(OH)2 = 0.111 mol/L or 0.111 M

4 0

4 years ago

A 150mL sample of NaOH has the pH of 9.5. On a Bunsen burner, 100mL of water was boiled from the NaOH solution. What is the expe

max2010maxim [7]

Find the [OH-] in the solution. The pH is 9.5, so the pOH is 14 - 9.5 = 4.5.
[OH-] = 10^-4.5 M
Now use the dilution equation to find the new [OH-] after the volume is reduced from 150 mL to 50 mL:
M1V1 = M2V2
M1 = 10^-4.5 M
V1 = 150 mL
M2 = ?
V2 = 50 mL

(10^-4.5)(150) = M2(50)
M2 = 9.5 x 10^-5 M ≈ 1 • 10^-4 (We can only use one sig fig, because the pH was given to one decimal place.)

Now use this [OH-] to find pOH:
pOH = -log(1 x 10^-4) = 4.0

14 - pOH = pH, so the expected pH for the new solution is 10.

7 0

3 years ago

Which is more concentrated, a solution containing 10g of NaCl in 100 g

Pavel [41]

Answer:

The answer is the solution containing the 90g of water.

Explanation:

Because both solutions have the same amount of the sodium chloride, the concentration would be the same if they both had the same amount of water.

Because the second solution has less water, there is more of the sodium chloride per each drop of water.

I hope this helps :)

4 0

3 years ago

Why do metals differ in specific heat? Why is Al much higher than gold?

soldier1979 [14.2K]

Specific heat is the amount of energy needed to increase the temperature per unit mass in 1°C.

The nature of the elements or compounds (metalic elements in this case) determines the transference of heat inside the body of the object. The mechanism of heat transfer inside the metals is conductivty. The more compact and denser the metal, the closer the atoms and the faster the transference of heat by conductivity and the lower the specific heat.

Then, the reason why specific heat of Al is much lower than gold, is that gold is much denser than Al.

6 0

4 years ago