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3 years ago

What are some examples of physical changes?

2 answers:

5 0

Answer: Melting of ice to water is a physical change. Evaporation, Freezing are also physical change. Cutting of wood, breaking of glass are also examples. Any change in size and phase but does not change its chemical composition is an example of a physical change.

Explanation:

Ludmilka [50]3 years ago

3 0

Some examples of physical changes are:

Breaking a glass

Chopping wood

Tearing paper

Mixing sand and water

Melting an ice cube

These all are physical changes because the composition of the matter does not change.

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You are given an aqueous solution and are asked to analyze it for the presence (or absence) of Ag+(aq), Ca2+(aq), and/or Hg2+(aq

pantera1 [17]

Answer:

Explanation:

In the first step, hydrochloric acid (HCl) is added to the solution. In this case the equilibrium that could take place is:

Ag⁺(aq) + Cl⁻(aq) ↔ AgCl(s)

But no precipitate was formed, so Ag⁺(aq) is absent.

By adding H₂SO₄(aq) the next equilibrium that could take place is:

Ca⁺²(aq) + SO₄⁻²(aq) ↔ CaSO₄(s)

A white precipitate was formed, so Ca⁺² is present in the solution.

The following could take place after adding H₂S(aq):

Hg²⁺(aq) + S⁻² ↔ HgS(s)

A black precipitate formed, so Hg⁺² is present as well.

6 0

3 years ago

A bottle of wine contains 12.8% ethanol by volume. The density of ethanol (CH3OH) is 0.789 g/cm. Calculate the concentratic etha

Scrat [10]

Answer : The mass percent of ethanol is, 10.38 % and the molality of ethanol is, 2.52 mole/kg

Explanation :

In wine, the solute and solvent are ethanol and water respectively.

Given :

12.8 % ethanol by volume means 12.8 mL ethanol present in 100 mL solution.

Volume of ethanol = 12.8 mL

Volume of solution = 100 mL

Volume of water = 100 - 12.8 = 87.2 mL

Density of ethanol = $0.789g/cm^3=0.789g/mL$

Density of water = 1 g/mL

Now we have to calculate the mass of ethanol and water.

$\text{Mass of ethanol}=\text{Density of ethanol}\times \text{Volume of ethanol}=0.789g/mL\times 12.8mL=10.1g$

and,

$\text{Mass of water}=\text{Density of water}\times \text{Volume of water}=1g/mL\times 87.2mL=87.2g$

Now we have to calculate the total mass of 100 mL of wine.

Total mass of 100 mL of wine = 10.1 + 87.2 = 97.3 g

Now we have to calculate the mass percent of ethanol.

$\text{Mass of percent of ethanol}=\frac{\text{Mass of ethanol}}{\text{Total mass of solution}}\times 100$

$\text{Mass of percent of ethanol}=\frac{10.1g}{97.3g}\times 100=10.38\%$

The mass percent of ethanol is, 10.38 %

Now we have to calculate the molality.

$Molality=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Mass of solvent}}$

Molar mass of ethanol = 46 g/mole

$Molality=\frac{10.1g\times 1000}{46g/mole\times 87.2g}=2.52mole/kg$

The molality of ethanol is, 2.52 mole/kg

6 0

4 years ago

How does an increase in temperature affect a chemical reaction??

blsea [12.9K]

An increase in the temperature will speed up the reaction by increasing the frequency and efficiency of the collisions of molecules.

8 0

3 years ago

each body cell of a goldfish contains 94 chromosomes.how many chromosomes are contained in a goldfish sex cell?

Shalnov [3]

47 I believe not 100% sure

8 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

4 years ago