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3 years ago

Y is it necessary to use clear colourless oil in the determination of melting point of naphthalene

Chemistry

1 answer:

Nastasia [14]3 years ago

6 0

Answer:it is necessary to use colourless

Explanation: A pure substance generally has a melting range (the difference between the temperature where the sample starts to melt and the temperature where melting is complete) of one or two degrees. Impurities tend to depress and broaden the melting range so the purified sample should have a higher and smaller melting range than the original, impure sample

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If 38.6 grams of iron react with an excess of bromine gas, what mass of FeBr2 can form?

Yuki888 [10]

Answer:

›› FeBr2 molecular weight. Molar mass of FeBr2 = 215.653 g/mol. This compound is also known as Iron(II) Bromide. Convert grams FeBr2 to moles or moles FeBr2 to grams. Molecular weight calculation: 55.845 + 79.904*2 ›› Percent composition by element

Explanation:

5 0

3 years ago

PCl3(g) + Cl2(g) ⇋ PCl5(g) Kc = 91.0 at 400 K. What is the [Cl2] at equilibrium if the initial concentrations were 0.24 M for PC

Dmitry_Shevchenko [17]

Answer:

[Cl₂] in equilibrium is 1.26 M

Explanation:

This is the equilibrium:

PCl₃(g) + Cl₂(g) ⇋ PCl₅(g)

Kc = 91

So let's analyse, all the process:

PCl₃(g) + Cl₂(g) ⇋ PCl₅(g)

Initially 0.24 M 1.50M 0.12 M

React x x x

Some amount of compound has reacted during the process.

In equilibrium we have

0.24 - x 1.50 - x 0.12 + x

As initially we have moles of product, in equilibrium we have to sum them.

Let's make the expression for Kc

Kc = [PCl₅] / [Cl₂] . [PCl₃]

91 = (0.12 + x) / (0.24 - x) ( 1.50 - x)

91 = (0.12 + x) / (0.36 - 0.24x - 1.5x + x²)

91 (0.36 - 0.24x - 1.5x + x²) = (0.12 + x)

32.76 - 158.34x + 91x² = 0.12 +x

32.64 - 159.34x + 91x² = 0

This a quadratic function:

a = 91; b= -159.34; c = 32.64

(-b +- √(b² - 4ac)) / 2a

Solution 1 = 1.5

Solution 2 = 0.23 (This is our value)

So [Cl₂] in equilibrium is 1.50 - 0.23 = 1.26 M

5 0

4 years ago

A bond between a nonmetal and a nonmetal is called a(n)

Pani-rosa [81]

Answer:

answer: B

Explanation:

becaucse it is B

7 0

3 years ago

Read 2 more answers

He reaction produces 1.6 g of gas in 30 seconds.Calculate the mean rate of the reaction in the first 30 seconds.Use the equation

devlian [24]

Answer:

Mean rate of reaction produced = 0.533 g/sec (approx.)

Explanation:

Given:

Reaction produced = 1.6 gram

Time taken = 30 sec

Find:

Mean rate of reaction produced

Computation:

Mean rate of reaction produced = Reaction produced / Time taken

Mean rate of reaction produced = 1.6 / 30

Mean rate of reaction produced = 0.533 g/sec (approx.)

5 0

3 years ago

What is the minimum (non-zero) thickness of a benzene (n = 1.501) thin film that will result in constructive interference when v

ad-work [718]

Explanation:

At each reflecting surface (benzene and glass) there will be 180 degree phase change.

Now, for constructive interference the optical path in benzene is $\lambda$ .

Formula to calculate thickness of a benzene thin film is as follows.

Optical path length through benzene ( $\lambda$ ) = $2 \times n \times d$

Hence, substituting the given values into the above formula as follows.

Optical path length through benzene = $2 \times n \times d$

d = $\frac{\text{Optical path length through benzene}}{2 \times n}$

= $\frac{\lambda}{2 \times n}$

= $\frac{615 \times 10^{-9}}{2 \times 1.501}$ (as 1 nm = $10^{-9}m$

= 204.9 m

Thus, we can conclude that minimum thickness of benzene is 204.9 m.

4 0

3 years ago

Y is it necessary to use clear colourless oil in the determination of melting point of naphthalene​

Y is it necessary to use clear colourless oil in the determination of melting point of naphthalene