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3 years ago

Ice melts to form water. And water freezes to form ice. Choose the TRUE statement about these changes.

Chemistry

2 answers:

Dmitrij [34]3 years ago

4 0

Answer:

A. Both freezing and melting are physical changes.

Explanation:

Even if you were to freeze water, the molecules are still water molecules, and vise versa with melting it.

vovikov84 [41]3 years ago

3 0

Answer: Option A) Both melting and freezing are physical changes.

Explanation:

A physical change is one which is easily reversible and in which no new substances are formed.

Hence, since ice melts to form water (melting), and water freezes to form ice back (freezing), both melting and freezing are easily reversible and do not form new products.

Thus, both melting and freezing are physical changes.

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How many moles of ba(oh)2 are present in 275 ml of 0.200 m ba(oh)2?

DENIUS [597]

You have to put your attention to the unit of concentration. It is expressed in terms of molarity, which is represented in M. It is the number of moles solute per liter solution. So, you simply have to multiply the molarity with the volume in liters.

Volume = 275 mL * 1 L/1000 mL = 0.275 L
Moles Ba(OH)₂ = (0.200 M)(0.275 L) = 0.055 mol

6 0

4 years ago

Why cant magnesium ions be detected in a flam test?

Dmitry [639]

When magnesium ion doesn't give any characteristics colour with the flame test as electronic transisitons do not give out visible light.

6 0

3 years ago

Liquid hexane

maks197457 [2]

Answer: The mass of $H_2O$ produced is 2.52 g

Explanation:

The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ ......(1)

For hexane:

Given mass of hexane = 1.72 g

Molar mass of hexane = 86.18 g/mol

Putting values in equation 1, we get:

$\text{Moles of hexane}=\frac{1.72g}{86.18g/mol}=0.020mol$

For oxygen gas:

Given mass of oxygen gas = 8.0 g

Molar mass of oxygen gas= 32 g/mol

Putting values in equation 1, we get:

$\text{Moles of water}=\frac{8.0g}{32g/mol}=0.25mol$

The chemical equation for the combustion of hexane follows:

$2C_6H_{14}+19O_2\rightarrow 12CO_2+14H_2O$

By stoichiometry of the reaction:

If 2 moles of hexane reacts with 19 moles of oxygen gas

So, 0.020 moles of hexane will react with = $\frac{19}{2}\times 0.020=0.19mol$ of oxygen gas

As the given amount of oxygen gas is more than the required amount. Thus, it is present in excess and is considered as an excess reagent.

Thus, hexane is considered a limiting reagent because it limits the formation of the product.

By the stoichiometry of the reaction:

If 2 moles of hexane produces 14 moles of $H_2O$

So, 0.020 moles of hexane will produce = $\frac{14}{2}\times 0.020=0.14mol$ of $H_2O$

We know, molar mass of $H_2O$ = 18 g/mol

Putting values in above equation, we get:

$\text{Mass of }H_2O=(0.14mol\times 18g/mol)=2.52g$

Hence, the mass of $H_2O$ produced is 2.52 g

4 0

3 years ago

A gas that exerts a pressure of

spayn [35]

Answer:

3.089 L

Explanation:

From the given information, provided that the no of moles and the temperature remains constant;

$P_1$ = 15.6 psi

$V_1$ = ???

$P_2$ = 25.43 psi

$V_2$ = 1.895 L

Using Boyle's law:

$P_1V_1 =P_2V_2 \\ \\ V_1 = \dfrac{P_2V_2}{P_1} \\ \\ V_1 = \dfrac{25.43 \times 1.895}{15.6} \\ \\ \mathbf{ V_1 = 3.089 \ L}$

4 0

3 years ago

Consider the chemical equations shown here.

vichka [17]

P₄0₆ $_{s}$ + 20₂ $_{g}$ ⇒ P₄0₁₀ $_{s}$

Explanation:

The overall equation for the reaction that produces P₄0₁₀ is :

P₄0₆ $_{s}$ + 20₂ $_{g}$ ⇒ P₄0₁₀ $_{s}$

Now let us derive this equation:

Given equations:

P₄ $_{s}$ + 30₂ $_{g}$ ⇒ P₄0₆ $_{s}$ equation 1;

P₄ $_{s}$ + 50₂ $_{g}$ ⇒ P₄0₁₀ $_{s}$ equation 2;

To get the overall combined equation, the equation 1 must be reversed and added to equation 2:

P₄0₆ $_{s}$ ⇒ P₄ $_{s}$ + 30₂ $_{g}$ equation 3

equation 2:

P₄ $_{s}$ + 50₂ $_{g}$ + P₄0₆ $_{s}$ ⇒ P₄0₁₀ $_{s}$ + P₄ $_{s}$ + 30₂ $_{g}$

cancelling specie that appears on both sides and removing excess oxygen gas on the reactant side gives;

P₄0₆ $_{s}$ + 20₂ $_{g}$ ⇒ P₄0₁₀ $_{s}$

learn more:

Net equation brainly.com/question/2947744

#learnwithBrainly

5 0

3 years ago