When the equation __H2O2 --> __H2O + __O2 Is completely balanced, the sum of all the coefficients will be A) 5 B) 8 C) 3 D) 4

An unknown amount of acid can often be determined by adding an excess of base and then back-titrating the excess. A 0.3471−g sam

MAXImum [283]

Explanation:

The given data is as follows.

Mass of mixture = 0.3471 g

As the mixture contains oxalic acid and benzoic acid. So, oxalic acid will have two protons and benzoic acid has one proton.

This means oxalic acid will react with 2 moles of NaOH and benzoic acid will react with 1 mole of NaOH.

Hence, moles of NaOH in 97 ml = $\frac{0.1090 \times 97}{1000}$

= $10.573 \times 10^{-3} mol$

Moles of HCl in 21.00 ml = $\frac{0.2060 \times 21}{1000}$

= $4.326 \times 10^{-3}$ mol

Therefore, total moles of NaOH that reacted are as follows.

$10.573 \times 10^{-3} mol$ - $4.326 \times 10^{-3} mol$

= $6.247 \times 10^{-3}$ mol

So, total 3 mole of NaOH will react with 1 mole of mixture. Therefore, number of moles of NaOH reacted with benzoic acid is as follows.

$\frac{6.247 \times 10^{-3}}{3}$

= $2.082 \times 10^{-3}$ mol

Since, molar mass of NaOH is 40 g/mol. Therefore, calculate the mass of NaOH as follows.

$2.082 \times 10^{-3} mol \times 40 g/mol$

= $83.293 \times 10^{-3}$ g

= 0.0832 g

Whereas molar mass of benzoic acid is 122 g/mol.

Therefore, 40 g NaOH = 122 g benzoic acid

So, 0.0832 g NaOH = $\frac{122 g}{40 g} \times 0.0832 g$

= 0.253 g

Hence, calculate the % mass of benzoic acid as follows.

$\frac{0.253 g}{0.3471 g} \times 100$

= 73.10%

Thus, we can conclude that mass % of benzoic acid is 73.10%.

4 0

3 years ago

When 4.41g of phosphoric acid (H3PO4) react with 9.25g of barium hydroxide, water and insoluble barium phosphate form. [T/I-7] a

AnnZ [28]

Answer:

2 H₃PO₄(aq) + 3 Ba(OH)₂(aq) ⇒ Ba₃(PO₄)₂(s) + 6 H₂O(l)

Explanation:

Let's consider the unbalanced equation that occurs when phosphoric acid reacts with barium hydroxide to form water and barium phosphate. This is a neutralization reaction.

H₃PO₄(aq) + Ba(OH)₂(aq) ⇒ Ba₃(PO₄)₂(s) + H₂O(l)

We will balance it using the trial and error method.

First, we will balance Ba atoms by multiplying Ba(OH)₂ by 3 and P atoms by multiplying H₃PO₄ by 2.

2 H₃PO₄(aq) + 3 Ba(OH)₂(aq) ⇒ Ba₃(PO₄)₂(s) + H₂O(l)

Finally, we will get the balanced equation by multiplying H₂O by 6.

2 H₃PO₄(aq) + 3 Ba(OH)₂(aq) ⇒ Ba₃(PO₄)₂(s) + 6 H₂O(l)

3 0

3 years ago

The concentration of hydroxide ions is greater than the concentration of hydronium ions for acidic solutions.

Katena32 [7]

Answer:

True

Explanation:

It's true because the pH is a measure of how basic or acid a solution is. In an acidic medium, the pH scales goes from 0 to 7. While in a basic medium goes from 7 to 14. The lower the pH value of the most acid the solution is.

1. The expression pH = -log(molar concentration of hydronium) allow to calculate the pH of a solution.

2. On the other hand, the expression pOH = -log(molar concentration of hydroxide) allow to determine the pOH of a solution.

The values of pH and pOH always obey the following expression:

pH + pOH = 14

Thus if for instance the pH becomes smaller the pOH must become bigger in order to fulfill the equation. Which means that the concentration of hydronium ions is greater than the hydroxide concentration.

For example, in an acidic medium:

if pH= 3, pOH= 11

In this case the molar concentration of hydronium is 0,001M. And the molar concentration of hydroxide ions is just 0,00000000001M.

6 0

3 years ago

Read 2 more answers

Consider this reaction 2Mg(s)+O2(g) ———> 2MgO(s) What volume (in milliners) of gas is required to react with 4.03 g Mg at STP

nydimaria [60]

The volume of a gas that is required yo react with 4.03 g mg at STP is 1856 ml

calculation/

calculate the moles of Mg used

moles=mass/molar mass

moles of Mg is therefore=4.03 g/ 24.3 g/mol=0.1658 moles

by use of mole ratio of Mg:O2 from the equation which is 2:1

the moles 02=0.1679 x1/20.0829 moles

at STP 1 mole of a gas= 22.4 l

0.0895 moles=? L

by cross multiplication

=0.0895 moles x22.4 l/ 1 mole=1.8570 L

into Ml = 1.8570 x1000=1856 ml approximately to 1860

6 0

3 years ago

How many significant figures are in the measurement 40, 500 mg? a) two b) three c) four d) five

emmainna [20.7K]

I believe there are 3 significant figures B.

8 0

2 years ago