Which of the following observations likely describes a physical change?

Is the following a chemical change or a physical change?

spayn [35]

It's a Chemical Change

8 0

3 years ago

Torrey's neighbor told her that a marble rolling down a hill increases in velocity as it rolls down, but does not increase in ki

ziro4ka [17]

Answer:

Torrey's neighbour is incorrect because increase in kinetic energy is proportional to velocity. If the velocity increases so will the object's kinetic energy. Because the mass is constant, if the velocity increases, so does the kinetic energy.

6 0

3 years ago

What is the term for a liquid composed of polar molecules?

IrinaVladis [17]

A dissolving liquid composed of polar molecules is a polar solvent.

The distinction of polar and non-polar liquids is important because the like dissolves like rule. This rule states that the solubility is greater when the polarity of the liquid is similar to the polarity of the solute.

So, to dissolve polar compounds (e.g. ionic compounds) you should use polar solvents (e.g. water).

Answer: polar solvent

7 0

3 years ago

Barium sulfate is made by the following reaction.

ipn [44]

Answer:

%age Yield = 96 %

Explanation:

The balance chemical equation for given double replacement reaction is,

Ba(NO₃)₂ + Na₂SO₄ → BaSO₄ + 2 NaNO₃

Step 1: Calculate moles of Ba(NO₃)₂:

Moles = Mass / M.Mass

Moles = 75.1 g / 261.33 g/mol

Moles = 0.2873 moles of Ba(NO₃)₂

Step 2: Find out moles of BaSO₄ formed:

According to balance chemical equation,

1 mole of Ba(NO₃)₂ produced = 1 mole of BaSO₄

So,

0.2873 moles of Ba(NO₃)₂ will produce = X moles of BaSO₄

Solving for X,

X = 0.2873 mol × 1 mol / 1 mol

X = 0.2873 moles of BaSO₄

Step 3: Calculate Theoretical Mass of BaSO₄:

Mass = Moles × M.Mass

Mass = 0.2873 mol × 233.38 g/mol

Mass = 67.07 g of BaSO₄

Step 4: Calculate %age Yield as:

Theoretical Yield = 67.07 g

Actual Yield = 64.4 g

%age Yield = ???

Formula Used:

%age Yield = (Actual Yield ÷ Theoretical Yield) × 100

Putting Values,

%age Yield = (64.4 g ÷ 67.07 g) × 100

%age Yield = 96.01 % ≈ 96 %

6 0

3 years ago

- How many grams are in 4.6 x 1016 molecules of phosphorus trichloride (PCI)?

MariettaO [177]

Answer:

0.0000101 grams.

Explanation:

First of all, use Avogadro's number to convert from molecules to moles.

Avogadro's number is 6.02 x 10^23.

Second of all, to convert from moles to grams, find the substance formula of phosphorus trichloride. After finding the substance formula, then find the molar mass of phosphorus trichloride.

Phosphorus trichloride is PCl3

Now find the molar mass of PCl3

P = 31.0 amu

Cl = 35.5 amu

They are three chlorine atoms and one phosphorus atom. So you do this.

31.0(1) + 35.5(3) = 137.5 g/mol

Now use dimensional analysis to show your work

4.6 x 10^16 grams of PCl3 * 1 mol/ 6.02 x 10^23 * 137.5 g/mol / 1 mol

The grams and the moles cancel out.

So now do [(4.6 x 10^16) / (6.02 x 10^23)] x 137.5

and you will get 0.000010507

4.6 has the fewest digits which is 2.

So use sig figs and the answer rounds to the nearest millionths.

0.000010507 rounds to 0.0000101

So the final answer is 0.0000101 grams(don't forget the units)

Hope it helped!

4 0

3 years ago