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Masteriza [31]
2 years ago
5

A quality control chemist at Dow Chemical tried to determine purity of NaOH using titration. He measured out 0.500 g NaOH sample

and dissolved it in 20 mL water. 22.5 mL of a 0.500 mol/L HCl solution was used to reach the end point. Assume the impurity did not react with HCl, what is the % purity of this NaOH sample?
Chemistry
1 answer:
Alex17521 [72]2 years ago
3 0

Answer:

89.94 %

Explanation:

Considering:

Molarity=\frac{Moles\ of\ solute}{Volume\ of\ the\ solution}

Or,

Moles =Molarity \times {Volume\ of\ the\ solution}

Given :

For HCl :

Molarity = 0.500 M

Volume = 22.5 mL

The conversion of mL to L is shown below:

1 mL = 10⁻³ L

Thus, volume = 22.5×10⁻³ L

Thus, moles of HCl :

Moles=0.500 \times {22.5\times 10^{-3}}\ moles

Moles of HCl = 0.01125 moles

The reaction of NaOH and HCl is:

NaOH + HCl ⇒ NaCl + H₂O

Moles of HCl = Moles of NaOH

<u>Thus, Moles of NaOH = 0.01125 moles</u>

Molar mass of NaOH = 39.997 g/mol

The formula for the calculation of moles is shown below:

moles = \frac{Mass\ taken}{Molar\ mass}

Thus,

0.01125\ moles= \frac{Mass}{39.997\ g/mol}

Mass of NaOH= 0.4497\ g

Total mass = 0.500 g

<u>% purity = ( 0.4497 / 0.500 ) × 100 = 89.94 %</u>

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A 0.500 g sample of tin (Sn) is reacted with oxygen to give 0.534 g of product. What is the empirical formula of the oxide?
REY [17]

Answer:

Sn_2O

Explanation:

Hello,

In this case, given that the mass of the product is 0.534 g, we can infer that the percent composition of tin is:

\%Sn=\frac{0.500g}{0.534g}*100\%\\ \\\%Sn=93.6\%

Therefore, the percent composition of oxygen is 6.4% for a 100% in total. Thus, with such percents we compute the moles of each element in the oxide:

n_{Sn}=93.6gSn*\frac{1molSn}{118.8gSn} =0.788molSn\\\\n_O=6.4gO*\frac{1molO}{16gO}=0.4molO

In such a way, for finding the smallest whole number we divide the moles of both tin and oxygen by the moles of oxygen as the smallest moles:

Sn:\frac{0.788}{0.4}=2\\ \\O:\frac{0.4}{0.4}=1

Therefore, the empirical formula is:

Sn_2O

Best regards.

8 0
2 years ago
For which of the following properties does sodium have a larger value than rubidium? Select all that apply.
Doss [256]

Answer:

Ionization energy

Electronegativity

Explanation:

-due to its smaller ionic radius....the electron in the outter most shell tends to expierence a stronger nuclear attraction...which makes it harder to remove the electron from the sodium atom

-Rubidium has lesser ionization energy because its (i) affected by its larger ionic radius which tends to lessen the nuclear attraction ...hence making it easier to remove the electron...(ii)and also by the screening effect done by the inner shells, which also tends to lessen the nuclear attraction.

Sodium has a higher electronegativity than rubidium;

Electronegativity is the charge density of electrons in an atom...in which its high when the atomic radius is smaller...

So hence due to the sodium atomic radius being smaller...it tends to have a higher charge density than rubidium....which then gives it a higher electronegativity value

4 0
2 years ago
Compare and contrast steak and juice​
blsea [12.9K]
Steak is a meat and juice is a liquid
5 0
2 years ago
Write down the dissolution equation for rubidium chromate dissolving in water. (Chromate is a polyatomic ion with the formula Cr
ycow [4]

Answer:

Four moles of the cation

Explanation:

2Rb2CrO4(s)<--------> 4Rb^+(aq) + 2CrO4^2-(aq)

Now looking at the reaction equation, it can be seen that one mole of rubidium chromate contains two moles of rubidium ions and one mole of chromate ions.

The dissolution of two moles of rubidium chromate should then yield four moles of rubidium ions and two moles of chromate ions since the ratio of ions present is 2:1.

This explains the reaction equation written above for the dissolution of two moles of rubidium chromate as shown.

5 0
2 years ago
eleanor purchased $2568 worth of stock and paid her broker a 0.5% fee. She sold the stock when the stock price increased to 3928
Mrrafil [7]

Answer: $1338.16

Explanation: Total cost of stock= $2568

Total cost of stock including the brokerage =2568+\frac{0.5}{100}\times {2568}=2580.84$

Selling price of stock = $3928

Selling price of stock including trading fee=($3928-$7)=$3919

Net Proceeds = Net selling price of stock - Cost Price of stock

Net Proceeds = ($3919 - $2580.84) = $1338.16


5 0
2 years ago
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