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3 years ago

how much heat will be absorbed by 25g of chloroform when its temperature started at 67.0C and after it was 112.0C

Chemistry

1 answer:

snow_tiger [21]3 years ago

8 0

Hello friend ☺

ΔH = MCΔT

ΔH = to the amount of energy or change in energy (J)

mass of water

C = waters specific heat capacity

ΔT = change in temperature

and so ΔH = 25 × 4.18 × ( 112-67 ) J = 4702.5 J

Thanks ❤

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What is the freezing point of a solution of 0.5 mol of LiBr in 500 mL of water? (Kf = 1.86°C/m) –1.86°C –7.44°C –5.58°C –3.72°C

tresset_1 [31]

Answer:

Last choice: - 3.72°C

Explanation:

The freezing point depression in a solvent is a colligative property: it depends on the number of solute particles.

The equation to predict the freezing point depression in a solvent is:

ΔTf = Kf × m × i

Where,

ΔTf is the freezing point depression of the solvent,

m is the molality,

Kf is the cryoscopic molal constant of the solvent, and i is the Van'f Hoff factor, which is the number of ions produced by each unit formula of the ionic compound.

The calcualtions are in the attached pdf file. Please, open it by clicking on the image of the file.

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3 years ago

How is copper sulphate different to copper sulphide in terms of the elments it contains

son4ous [18]

Answer:

An Element is a substance made up of only one type of atom as like gold, copper, oxygen, etc.

Copper sulphate with molecular formula $(CuSO_4)$ , the elements are copper, sulphur and oxygen. It is formed by combination of $Cu^{2+}$ cation and $SO_4^{2-}$ anion.

Copper sulphide with molecular formula $(CuS)$ , the elements are copper and sulphur. It is formed by combination of $Cu^{2+}$ cation and $S^{2-}$ anion.

6 0

3 years ago

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masya89 [10]

The answer is A.
A pure substance is pure, so it cannot be separated in most cases.

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3 years ago

The [-oh) in a sample of egg whites is 6.3 x 10-7 m. what is the [h3o+] in these egg whites?

Kamila [148]

The hydrogen ion concentration [H3O+] in an egg white containing 6.3 × 10-⁷M of [OH-] is 1.5 × 10-⁸M.

<h3>How to calculate [H3O+]?</h3>

The hydrogen ion concentration of a solution can be calculated as follows:

pOH = - log [OH-]

pOH = - log [6.3 × 10-⁷M]

pOH = - [-6.2]

pOH = 6.2

Since pOH + pH = 14

pH = 14 - 6.2

pH = 7.8

pH = - log [H3O+]

7.8 = - log [H3O+]

[H3O+] = 10-⁷:⁸

[H3O+] = 1.5 × 10-⁸M

Therefore, the hydrogen ion concentration [H3O+] in an egg white containing 6.3 × 10-⁷M of [OH-] is 1.5 × 10-⁸M.

Learn more about hydrogen ion concentration at: brainly.com/question/15082545

7 0

2 years ago

Perform the calculation and record the answer with the correct number of significant figures.

kotykmax [81]

The question is incomplete, here is the complete question:

A. (6.5-6.10)/3.19

B. (34.123 + 9.60) / (98.7654 - 9.249)

Answer:

For A: The answer becomes 0.1

For B: The answer becomes 0.4884

Explanation:

Significant figures are defined as the figures present in a number that expresses the magnitude of a quantity to a specific degree of accuracy.

Rules for the identification of significant figures:

Digits from 1 to 9 are always significant and have infinite number of significant figures.
All non-zero numbers are always significant. For example: 664, 6.64 and 66.4 all have three significant figures.
All zeros between the integers are always significant. For example: 5018, 5.018 and 50.18 all have four significant figures.
All zeros preceding the first integers are never significant. For example: 0.00058 has two significant figures.
All zeros after the decimal point are always significant. For example: 2.500, 25.00 and 250.0 all have four significant figures.
All zeroes used solely for spacing the decimal point are not significant. For example: 10000 has one significant figure.

Rule applied for addition and subtraction:

The least precise number present after the decimal point determines the number of significant figures in the answer.

Rule applied for multiplication and division:

In case of multiplication and division, the number of significant digits is taken from the value which has least precise significant digits

For A: (6.5-6.10)/3.19

This a a problem of subtraction and division.

First, the subtraction is carried out.

$\Rightarow \frac{6.5-6.10}{3.19}=\frac{0.4}{3.19}$

Here, the least precise number after decimal was 1.

$\Rightarrow \frac{0.4}{3.19}=0.125$

Here, the least precise number of significant digit is 1. So, the answer becomes 0.1

For B: (34.123 + 9.60) / (98.7654 - 9.249)

This a a problem of subtraction, addition and division.

First, the subtraction and addition is carried out.

$\Rightarow \frac{34.123+9.60}{98.7654-9.249}=\frac{43.723}{89.5164}=\frac{43.72}{89.516}$

Here, the least precise number after decimal in addition are 2 and in subtraction are 3

$\Rightarrow \frac{43.72}{89.516}=0.48840$

Here, the least precise number of significant digit are 4. So, the answer becomes 0.4884

6 0

3 years ago