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2 years ago

I need help with the 2nd part first gets brainlist

Chemistry

1 answer:

mixer [17]2 years ago

8 0

Answer:

7. 4H₂O

Elements: Hydrogen, Oxygen

Number of molecules: 4

Number of elements: 8 H, 4 O

Number of Atoms: 12

Explanation:

The elements are determined by the their symbol i.e. H = hydrogen.

The number of molecules is determined by the coefficient ( the number in front of everything, in this case 4).

The number of elements is determined by the coefficient and the subscripts. Multiply the coefficient by the subscript after each element. When there is no subscript, it is equal to 1. 4H₂ = 4x2 = 8; 4O = 4x1 = 4.

The number of atoms is all the individual elements added together. 8+4 = 12.

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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

3 years ago

Match the term with its description.

blagie [28]

Answer:

Pure substance B) Consists of a single element or type of compound.

Homogeneous A) Mixture that has its different components mixed evenly within the substance.

Heterogeneous D) Mixture that has its different components mixed unevenly within the substance.

Solution C) Liquid homogeneous mixture in which the solute is distributed evenly within the solvent.

Explanation:

Pure substances are a form of matter with definite constant composition and distinct properties. They consist of a single element or type of compound, as can be seen in its formula. Na, O₂, NaCl and H₂O are examples of pure substances.

When 2 or more pure substances are mixed together they form a mixture. If the mixture has its different components mixed evenly within the substance it is a homogeneous mixture. Whereas if the mixture has its different components mixed unevenly within the substance it is a heterogeneous mixture. The different parts observable in a heterogeneous mixture are known as phases.

In liquid homogeneous mixtures, we can recognize one or more substances that are in lower proportions (solutes) and one substance that is in greater proportion (solvent). This kind of mixture is known as a solution.

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3 years ago

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nataly862011 [7]

Answer:

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Explanation:

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olya-2409 [2.1K]

B is the correct answer.
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