PLEASE HELP!!

The phase change in which a substance changes from a liquid to a solid is A. freezing. B. melting. C. sublimation. D. condensati

vovangra [49]

freezing. Think of what happens when you put water in the freezer

4 0

3 years ago

Calculate the ph of the solution resulting by mixing 20.0 ml of 0.15 m hcl with 20.0 ml of 0.10 m koh

Aliun [14]

Answer:

1.60.

Explanation:

The no. of millimoles of HCl = MV = (0.15 M)(20.0 mL) = 3.0 mmol.

The no. of millimoles of KOH = MV = (0.10 M)(20.0 mL) = 2.0 mmol.

Since the no. of millimoles of HCl is larger than that of KOH. The solution is acidic.

∴ M of remaining HCl [H⁺] remaining = (NV)HCl - (NV)KOH/V total = (3.0 mmol) - (2.0 mmol) / (40.0 mL) = 0.025 M.

∵ pH = - log[H⁺]

∴ pH = - log[H⁺] = - log(0.025) = 1.602 ≅ 1.60.

5 0

3 years ago

Which of the following has a mass of 10.0 g?

Serjik [45]

Answer:

a. 0.119mol Kr

Explanation:

To solve this problem, we must understand that;

Mass = number of moles x molar mass

Molar mass of Kr = 83.3g/mol

Ar = 40g/mol

He = 4g/mol

Ne = 20.18g/mol

a0.119 mol Kr mass = 0.119 x 83.3 = 9.9g

b 0.400 mol Ar mass = 0.4 x 40 = 16g

C 1.25 mol He mass = 1.25 x 4 = 5g

d 2.02 mol Ne mass = 2.02 x 20.18 = 40.8

Krypton is the answer

5 0

3 years ago

The two methods in the lab for measuring the volume of a geometric solid object are weighing it on the balance and measuring it

Yakvenalex [24]

Answer:

Measuring with a ruler and using final volume minus initial volume

Explanation:

You can measure the volume of a geometric object by measuring its sides with a ruler and calculating the volume according to the corresponding formula for each object. For example, for a rectangular prism it would be

$volume=length*width*height$

You can also measure the volume of an object by measuring how much water it displaces. To do this you have to fill a measuring cylinder with enough water for the object to be completely submerged and take note of the volume. Then, add the object and note again the volume of the water+object. The difference between both is the volume of the object.

$Volume of the object= volume of water and object - volume of water$