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3 years ago

Why is it difficult to classify dissolving as simply a physical or a chemical change?

1 answer:

6 0

Dissolving an ionic compound is a chemical change. In contrast, dissolving sugar or another covalent compound is a physical change because chemical bonds are not broken and new products are not formed .Dissolving a solid in liquid, such as table salt in water, is a physical change because only the state of the matter has changed. Physical changes can often be reversed. ... It has not combined with the water to cause a chemical reaction

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In general how are word equations written to describe chemical equations

Alexus [3.1K]

<span>chemicals reacting are written on the left, what is formed is written on the right after the = sign

eg Copper + oxygen = copper oxide.
Hope this helps , mark as brainliest and say thanks THANKS..</span>

5 0

3 years ago

Chloral hydrate (C2H3Cl3O2) is a drug formerly used as a sedative and hypnotic.

Dmitrij [34]

Answer :

(a) The molar mass of $C_2H_3Cl_3O_2$ is, 165.5 g/mole

(b) The moles of $C_2H_3Cl_3O_2$ is, 3.02 moles

(c) The mass in grams of $2.0\times 10^{-2}$ mole chloral hydrate is, 3.31 g

(d) The number of chlorine atoms in 5.0 g chloral hydrate is, $5.4\times 10^{22}$

(e) The mass of chloral hydrate will be, 1.55 g

(f) The mass of exactly 500 molecules of chloral hydrate is, $1.99\times 10^{23}$

Explanation :

(a) To calculate the molar mass of chloral hydrate.

The formula of chloral hydrate is, $C_2H_3Cl_3O_2$

Atomic mass of carbon = 12 g/mole

Atomic mass of hydrogen = 1 g/mole

Atomic mass of oxygen = 16 g/mole

Atomic mass of chlorine = 35.5 g/mole

Now we have to determine the molar mass of chloral hydrate.

$\text{Molar mass of }C_2H_3Cl_3O_2$ =2(12g/mole)+3(1g/mole)+3(35.5g/mole)+2(16g/mole)=165.5g/mole[/tex]

The molar mass of $C_2H_3Cl_3O_2$ is, 165.5 g/mole

(b) Now we have to determine the moles of $C_2H_3Cl_3O_2$ .

$\text{Moles of }C_2H_3Cl_3O_2=\frac{\text{Mass of }C_2H_3Cl_3O_2}{\text{Molar mass of }C_2H_3Cl_3O_2}=\frac{500.0g}{165.5g/mole}=3.02moles$

The moles of $C_2H_3Cl_3O_2$ is, 3.02 moles

(c) Now we have to determine the mass in grams of $2.0\times 10^{-2}$ mole chloral hydrate.

$\text{Mass of }C_2H_3Cl_3O_2=\text{Moles of }C_2H_3Cl_3O_2\times \text{Molar mass of }C_2H_3Cl_3O_2$

$\text{Mass of }C_2H_3Cl_3O_2=(2.0\times 10^{-2}mole)\times (165.5g/mole)=3.31g$

The mass in grams of $2.0\times 10^{-2}$ mole chloral hydrate is, 3.31 g

(d) To calculate the number of chlorine atoms are in 5.0 g chloral hydrate.

First we have to determine the moles of $C_2H_3Cl_3O_2$ .

$\text{Moles of }C_2H_3Cl_3O_2=\frac{\text{Mass of }C_2H_3Cl_3O_2}{\text{Molar mass of }C_2H_3Cl_3O_2}=\frac{5g}{165.5g/mole}=0.03moles$

Now we have to calculate the number of chlorine atoms in chloral hydrate.

In $C_2H_3Cl_3O_2$ , there are, 2 carbon atoms, 3 hydrogen atoms, 3 chlorine atoms and 2 oxygen atoms.

As, 1 mole of $C_2H_3Cl_3O_2$ contains $3\times 6.022\times 10^{23}$ chlorine atoms

So, 0.03 mole of $C_2H_3Cl_3O_2$ contains $0.03\times 3\times 6.022\times 10^{23}=5.4\times 10^{22}$ chlorine atoms

The number of chlorine atoms in 5.0 g chloral hydrate is, $5.4\times 10^{22}$

(e) To calculate the mass of chloral hydrate would contain 1.0 g Cl.

As, $3\times 35.5g$ of chlorine present in 165.5 g of $C_2H_3Cl_3O_2$

So, 1 g of chlorine present in $\frac{165.5}{3\times 35.5}=1.55g$ of $C_2H_3Cl_3O_2$

The mass of chloral hydrate will be, 1.55 g

(f) To calculate the mass of exactly 500 molecules of chloral hydrate.

As, $6.022\times 10^{23}$ molecules of chloral hydrate has 165.5 g mass of chloral hydrate

So, 500 molecules of chloral hydrate has $\frac{6.022\times 10^{23}}{500}\times 165.5=1.99\times 10^{23}$ mass of chloral hydrate

The mass of exactly 500 molecules of chloral hydrate is, $1.99\times 10^{23}$

3 0

3 years ago

A backpacker collects snow at 0°C, and places it in a cooking pot on a camp stove. It takes 643 kJ of heat energy to melt the sn

frutty [35]

Answer:

mass (m) of the snow that the backpacker collected= 0.855 kg

Explanation:

Given that:

Q = 643 kJ = 643000 J

ΔHfusion = 6.02 kJ/mol = 6020 J/mol

number of mole of water H2O = $\frac{mass (m)}{18}$

c = 4.18 J/g⋅K

ΔT = 100 K

Since there is a phase change from solid to liquid; then :

$Q =$ $Q_s + Q_l$

ΔH = $\frac{q}{mol}$

However without the given mass; we substitute $\frac{m}{18}$ for the number of moles; so:

Q = $\delta H * \frac{m}{18}$ $+ m*c * \delta T$

$643000 =$ $6020 * \frac{m}{18}+ m * 4.18 * 100$

m = 855 g

m = 0.855 kg

mass (m) of the snow that the backpacker collected= 0.855 kg

8 0

3 years ago

The graph shows the amount of a gaseous product formed over time during two trials of a reaction. A different concentration of a

makkiz [27]

Trial 1 has a lower concentration of the reactant because the because the average rate of the reaction is lower.

<h3>What is a reaction?</h3>

The term reaction has to do with the combination of reactants in order to yield products. Now we know that the reaction profile is used to show the interaction that exists between the reactants and the products.

The y-axis of the graph is for the amount while the x axis of the graph is the reaction time. The rate of reaction is the time taken for a given amount of products to appear or for a given amount of reactants to disappear.

Thus, from the graph, we can see that trial 1 has a lower concentration of the reactant because the because the average rate of the reaction is lower.

Learn more about rate of reaction:brainly.com/question/24266729

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5 0

2 years ago

The diagram below shows students set-up for the preparation and collection of oxygen gas

dmitriy555 [2]

Answer:

iodine sodium preocide

Explanation:

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3 0

3 years ago