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SCORPION-xisa [38]
2 years ago
12

Through the complete electrolysis of a sample of pure water, a student collects 14.0 grams of hydrogen gas and 112.0 grams of ox

ygen gas. What mass of water (in grams), if it reacted completely, was initially present? (The electrolysis of water is the use of an electric current to decompose it into its component elements.) Report your answer to the nearest tenth
Chemistry
1 answer:
Vadim26 [7]2 years ago
6 0

Answer:

126.0g of water were initially present

Explanation:

The electrolysis of water occurs as follows:

2H₂O(l) ⇄ 2H₂(g) + O₂(g)

<em>Where 2 moles of water produce 2 moles of hydrogen and 1 mole of oxygen.</em>

<em />

To find the mass of water we need to determine moles of oxygen and hydrogen, thus:

<em>Moles Hydrogen:</em>

14.0g H₂ ₓ (1mol / 2g H₂) = 7 moles H₂

<em>Moles Oxygen:</em>

112.0g O₂ ₓ (1mol / 32g) = 3.5 moles O₂

Based on the chemical equation, the moles of water initially present were 7 moles (That produce 7 moles H₂ and 3.5 moles O₂). The mass of 7 moles of H₂O is:

7 moles H₂O * (18g / mol) =

<h3>126.0g of water were initially present</h3>
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Oxalic acid is a diprotic acid. calculate the percent of oxalic acid (h2c2o4) in a solid given that a 0.7984-g sample of that so
vlada-n [284]
This method of quantitative determination of percent purity is titrimetric reactions. These reactions most commonly involve neutralization reactions between an acid and a base. Then, we look at the neutralization reaction:

H₂C₂O₄ + 2 NaOH ⇒ Na₂C₂O₄ + 2 H₂O

So, we do the stoichiometric calculations. The important data we should know is the molar mass of oxalic acid which is equal to 90 g/mol.

(0.2283 mol/L NaOH * 0.3798 L * 1 mol H₂C₂O₄/ 2mol NaOH * 90 g/mol H₂C₂O₄) ÷ 0.7984 g *100%
= 488%

This is impossible. The purity can't be more than 100%. Looking at our calculations and the balance reaction, all steps were done correctly. So, I think there is some typographical error in the given. The mass of the sample should be 7.984 g. Then, the answer would be 48.87% purity.
5 0
2 years ago
Read 2 more answers
If a 0.4856 gram sample of khp is dissolved in sufficient water to prepare 250 ml of solution, and 25 ml of the solution require
dangina [55]

Mass of potassium hydrogen pthalate KHP is 0.4856 g, its molar mass is 204.22 g/mol, number of moles of KHP can be calculated as follows:

n=\frac{m}{M}

Here, m is mass and M is molar mass, putting the values,

n=\frac{0.4856 g}{204.22 g/mol}=0.00237 mol

This will be number of moles of NaOH at equivalent point.

Detailed calculations:

Molarity is defined as number of moles in 1 L of solution, for 250 mL of solution, molarity will be:

M=\frac{0.00237 mol}{250 \times 10^{-3}L}=0.009511 M

For 25 mL, apply dilution law as follows:

M_{1}V_{1}=M_{2}V_{2}

Putting the values,

0.009511\times 250=M_{2}\times 25 mL

On rearranging,

M_{2}=\frac{0.009511\times 250}{25}=0.09511 M

Convert molarity into number of moles,

n=M\times V=0.09511 mol/L\times 25\times 10^{-3}L=0.00237 mol

At equivalent point, number of moles of KHP will be equal to NaOH, thus, number of moles of NaOH will be 0.00237 mol.

Calculation for molarity:

Volume of NaOH is 18.75 mL, thus, molarity can be calculated as follows:

M=\frac{n}{V}

Putting the values,

M=\frac{0.00237 mol}{18.75\times 10^{-3}L}=0.1264 M

Therefore, molarity of NaOH is 0.1264 M

7 0
2 years ago
The electron in a ground-state H atom absorbs a photon of wavelength 97.20 nm. To what energy level does it move?
Lunna [17]

Answer:

E = h v = 6.626 x 10^{-34} x 97.20 x 10^{-9} = 6.44 x 10^{-41} J = 4.01 x 10^{-22} eV

n = Energy Level = -E^{0} / E = -13.6 / 4.01 x 10^{-22} = 3.39 x 10^{22} = 1.84 x 10^{11} energy level...

7 0
2 years ago
Imagine that a new polyatomic anion called "platoate" is invented. What would an acid of "platoate" be named?
o-na [289]
<h3>Answer:</h3>

                   Platoic Acid

<h3>Explanation:</h3>

                        While naming Carboxylic Acids we know that when the Carboxylic Acid looses proton it is converted into corresponding conjugate base called as Carboxylate.

Examples:

                        HCOOH           →           HCOO⁻  +  H⁺

                     Formic acid                     Formate Ion

                    H₃CCOOH           →           H₃CCOO⁻  +  H⁺

                     Acetic acid                       Acetate Ion

                    H₅C₂COOH           →           H₅C₂COO⁻  +  H⁺

                 Propanoic acid                       Propanoate Ion

Therefore, if the conjugate base is Platoate then the corresponding acid will be Platoic Acid means we will replace the -ate by -ic acid <em>i.e.</em>

                   RCOO⁻  +  H⁺        →            RCOOH

                   Platoate Ion                         Platoic Acid

8 0
2 years ago
Read 2 more answers
The concentration of sodium chloride in an aqueous solution that is 2.23 M and that has a density of 1.01 g/mL is __________% by
amm1812

Answer:

The concentration of sodium chloride in an aqueous solution that is 2.23 M and that has a density of 1.01 g/mL is 12.90% by mass

Explanation:

2.23 M aqueous solution of NaCl means there are 2.23 moles of NaCl in 1000 mL of solution.

We know that density is equal to ratio of mass to volume.

Here density of solution is 1.01 g/mL.

So mass of 1000 mL solution = (1.01\times 1000) g = 1010 g

molar mass of NaCl = 58.44 g/mol

So mass of 2.23 moles of NaCl = (2.23\times 58.44) g = 130.3 g

% by mass  is ratio of mass of solute to mass of solution and then  multiplied by 100.

Here solute is NaCl.

So % by mass of 2.23 M aqueous solution of NaCl = \frac{130.0}{1010}\times 100% = 12.90%

3 0
2 years ago
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