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2 years ago

Question 2

Chemistry

1 answer:

SVETLANKA909090 [29]2 years ago

3 0

D- Physical

Explanation:

A physical property is anything that has characteristics associated with a change in it's chemical composition

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What mass of potassium hypochlorite (FW-90.6 g/mol) must be added to 4.50 x 10 mL of water to give a solution with pH 10.20? [Ka

marta [7]

Answer : The mass of potassium hypochlorite is, 4.1 grams.

Explanation : Given,

pH = 10.20

Volume of water = $4.50\times 10^2ml=0.45L$

The decomposition of KClO will be :

$KClO\rightarrow K^++ClO^-$

Now the further reaction with water $(H_2O)$ to give,

$ClO^-+H_2O\rightarrow HClO+OH^-$

First we have to calculate the pOH.

$pH+pOH=14\\\\pOH=14-pH\\\\pOH=14-10.20=3.8$

Now we have to calculate the $OH^-$ concentration.

$pOH=-\log [OH^-]$

$3.8=-\log [OH^-]$

$[OH^-]=1.58\times 10^{-4}M$

Now we have to calculate the base dissociation constant.

Formula used : $K_b=\frac{K_w}{K_a}$

Now put all the given values in this formula, we get :

$K_b=\frac{1.0\times 10^{-14}}{4.0\times 10^{-8}}=2.5\times 10^{-7}$

Now we have to calculate the concentration of $ClO^-$ .

The equilibrium constant expression of the reaction is:

$K_b=\frac{[OH^-][HClO]}{[ClO^-]}$

As we know that, $[OH^-]=[HClO]=1.58\times 10^{-4}M$

$2.5\times 10^{-7}=\frac{(1.58\times 10^{-4})^2}{[ClO^-]}$

$[ClO^-]=0.0999M$

Now we have to calculate the moles of $ClO^-$ .

$\text{Moles of }ClO^-=\text{Molarity of }ClO^-\times \text{Volume of solution}$

$\text{Moles of }ClO^-=0.0999mole/L\times 0.45L=0.0449mole$

As we know that, the number of moles of $ClO^-$ are equal to the number of moles of KClO.

So, the number of moles of KClO = 0.0449 mole

Now we have to calculate the mass of KClO.

$\text{Mass of }KClO=\text{Moles of }KClO\times \text{Molar mass of }KClO$

$\text{Mass of }KClO=0.0449mole\times 90.6g/mole=4.07g\approx 4.1g$

Therefore, the mass of potassium hypochlorite is, 4.1 grams.

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2 years ago

Someone please help me with this

Inessa05 [86]

Answer:

With what???

Explanation:

I don't see anything.

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2 years ago

What is the melting point of stainless steel?

Mashcka [7]

"Alloy additions also suppress (lower) the melting range. Pure iron (Fe) has a fixed melting point of 1535°C, chromium (Cr) 1890°C and nickel (Ni) 1453°C compared to a range of 1400-1450 °C for type 304 stainless steel."

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3 years ago

What makes an inference different from a quess?

frosja888 [35]

Answer:

Explanation:

Inferences are not based on anything from the text while guesses are made only using the text. Inferences are based on evidence in the text while guesses are not. Inferences are made by only using major details from the text while guesses only use minor details.

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2 years ago

Blank c2h4 + blank o2 → blank co2 + blank h2o how many moles of o2 are in the chemical equation when balanced using the lowest w

umka21 [38]

The reaction is
C₂H₄ + O₂ → CO₂ + H₂O

To balance the equation, both side have same number of elements. Here,

In left hand side has in right hand side has

4 H atoms 2 H atoms

2 C atoms 1 C atom

2 O atoms 3 O atoms

First, we have to balance number of C atoms and number of H atoms in both side.
To balance C atoms, '2' should be added before CO₂ and to balance H atoms, '2' should be added before H₂O.
Then number of oxygen atoms is 2 x 2 + 2 = 6 in right hand side. So, 3 should be added before O₂ in left hand side.
After balancing the equation should be,

C₂H₄ + 3O₂ → 2CO₂ + 2H₂O

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2 years ago