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3 years ago

How are physical and chemical changes different

Chemistry

2 answers:

Wittaler [7]3 years ago

3 0

Answer:

physic

Explanation:

physical chnages are chnages to the appearance

chemical chnages are chnages like

color temperature chnaging fromna gas to a liquid etc

mariarad [96]3 years ago

3 0

Answer:

Explanation:

Physical changes do not change the properties of the initial substance. Physical changes are temporary. For eg if you boil water, it turns into vapor. It's chemical composition is still H2O but now its just in gas form instead of liquid but overtime that gas will condensate into water. SO physical changes are reversible most of the times.

Chemical changes change the properties of initial substance. Like burning wood, you can't really reverse this reaction because you can't go from coal to wood, its permanent change. So chemical changes are permanent changes. Like souring milk, acid-base reactions, rotting banana etc.

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Read 2 more answers

Calculate the molarity of a sugar solution if 4 liters of the solution contains 12 moles of sugar.

castortr0y [4]

Answer:

Explanation:

Molarity is one of the measures of the molar concentration of a solution, which can be calculated by using the formula below:

Molarity = number of moles ÷ volume

From the information given in this question, 4 liters of a solution contains 12 moles of sugar. This means that n = 12mol and V = 4L

Molarity = n/V

Molarity = 12/4

Molarity = 3

Hence, the molarity of the sugar solution is 3mol/L or 3M

8 0

2 years ago

When heat is applied to 80 grams of CaCO3, it yields 39 grams of B. Determine the percentage of the yield.

EleoNora [17]

The question is incomplete, the complete question is:

When heat is applied to 80 grams of CaCO3, it yields 39 grams of CaO Determine the percentage of the yield.

CaCO3→CaO + CO2

<u>Answer:</u> The % yield of the product is 87.05 %

<u>Explanation:</u>

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)

We are given:

Given mass of $CaCO_3$ = 80 g

Molar mass of $CaCO_3$ = 100 g/mol

Putting values in equation 1, we get:

$\text{Moles of }CaCO_3=\frac{80g}{100g/mol}=0.8mol$

For the given chemical reaction:

$CaCO_3\rightarrow CaO+CO_2$

By stoichiometry of the reaction:

If 1 mole of $CaCO_3$ produces 1 mole of CaO

So, 0.8 moles of $CaCO_3$ will produce = $\frac{1}{1}\times 0.8=0.8mol$ of CaO

We know, molar mass of $CaO$ = 56 g/mol

Putting values in above equation, we get:

$\text{Mass of CaO}=(0.8mol\times 56g/mol)=44.8g$

The percent yield of a reaction is calculated by using an equation:

$\% \text{yield}=\frac{\text{Actual value}}{\text{Theoretical value}}\times 100$ ......(2)

Given values:

Actual value of the product = 39 g

Theoretical value of the product = 44.8 g

Plugging values in equation 2:

$\% \text{yield}=\frac{39 g}{44.8g}\times 100\\\\\% \text{yield}=87.05\%$

Hence, the % yield of the product is 87.05 %

6 0

2 years ago