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3 years ago

What is the mole fraction of NaOH in an aqueous solution that contains 15% NaOH by mass?

Chemistry

1 answer:

zhenek [66]3 years ago

6 0

Answer:

0.074

Explanation:

15% means that in 100 g of solution 15 g sodium hydroxide is present.

Mass of water = 100 - 15 = 85 g

Number of moles of sodium hydroxide:

Number of moles = 15 g/40 g/mol

Number of moles = 0.375 mol

Number of moles of water:

Number of moles = 85 g/18 g/mol

Number of moles = 4.7 mol

Moles fraction of NaOH:

moles of NaOH/ moles of solvent + moles of solute

0.375 mol/ 0.375 mol+4.7mol

0.375 mol / 5.075 mol

0.074

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In a first-order decomposition reaction, 50.0% of a compound decomposes in 10.5 min.

mihalych1998 [28]

In this reaction 50% of the compound decompose in 10.5 min thus, it is half life of the reaction and denoted by symbol $t_{1/2}$ .

(a) For first order reaction, rate constant and half life time are related to each other as follows:

$k=\frac{0.6932}{t_{1/2}}=\frac{0.6932}{10.5 min}=0.066 min^{-1}$

Thus, rate constant of the reaction is $0.066 min^{-1}$ .

(b) Rate equation for first order reaction is as follows:

$k=\frac{2.303}{t_{1/2}}log\frac{[A_{0}]}{[A_{t}]}$

now, 75% of the compound is decomposed, if initial concentration $[A_{0} ]$ is 100 then concentration at time t $[A_{t} ]$ will be 100-75=25.

Putting the values,

$0.066 min^{-1}=\frac{2.303}{t}log\frac{100}{25}=\frac{2.303}{t}(0.6020)$

On rearranging,

$t=\frac{2.303\times 0.6020}{0.066 min^{-1}}=21 min$

Thus, time required for 75% decomposition is 21 min.

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3 years ago

Which description of salt is a physical property? (2 points)

jarptica [38.1K]

Product of mixing acids and bases describes salt is a physical property.

Product of mixing acids and bases

<u>Explanation:</u>

When an acid and a base are put together, they respond to kill the corrosive and base properties, creating a salt which portrays the physical property. The physical properties of table salt will be: Salt is a white cubic gem. At the point when the salt is unadulterated it clear.

It likewise shows up in white, dim or caramel shading relying on immaculateness. It is unscented yet has a solid salty taste. Fundamental salts contain the conjugate base of a feeble corrosive, so when they break down in the water, they respond with water to yield an answer with a pH more than 7.0.

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2 years ago

Moles of phosphorous in 15-35-15 fertilizer in 10g

guapka [62]

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saveliy_v [14]

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