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adell [148]
2 years ago
7

Why do experiments need to be repeatable?

Chemistry
2 answers:
Vilka [71]2 years ago
5 0
They need to be repeatable to prove that results from the expirement are viable, that it didn't just happen because of a series of things outside of the scientists control. Repetition just makes the expirement seem more credible. 
maw [93]2 years ago
3 0
If they were not repeatable people would think the experiment is not accurate. If it can be repeated than the data can prove a very valid point. 
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A 25.0 ml sample of 0.723 m hclo4 is titrated with a 0.27303 m koh solution. the h3o+ concentration after the addition of 66.2 m
tia_tia [17]
This doesn't need an ICE chart. Both will fully dissociate in water.

Assume HClO4 and KOH reacts with one another. All you need to do is determine how much HClO4 will remain after the reaction. Calculate pH.

Step 1:

write out balanced equation for the reaction

HClO4+KOH ⇔ KClO4 + H2O

the ratio of HClO4 to KOH is going to be 1:1. Each mole of KOH we add will fully react with 1 mole of HClO4

Step 2:

Determining the number of moles present in HClO4 and KOH

Use the molar concentration and the volume for each:
25 mL of 0.723 M HClO4

Covert volume from mL into L:
25 mL * 1L/1000mL = 0.025 L

Remember:

M = moles/L so we have 0.025 L of 0.723 moles/L HClO4

Multiply the volume in L by the molar concentration to get:

0.025L x 0.723mol/L = 0.0181 moles HClO4.

Add 66.2 mL KOH with conc.=0.273M
66.2mL*1L/1000mL = .0662 L
.0662L x 0.273mol/L = 0.0181 moles KOH

Step 3:

Determine how much HClO4 remains after reacting with the KOH.

Since both reactants fully dissociate and are used in a 1:1 ratio, we just subtract the number of moles of KOH from the number of moles of HClO4:

moles HClO4 = 0.0181; moles KOH = 0.0181, so 0.0181-0.0181 = 0

This means all of the HClO4 is used up in the reaction.

If all of the acid is fully reacted with the base, the pH will be neutral = 7.

Determine the H3O+ concentration:

pH = -log[H3O+]; [H3O+] = 10-pH = 10-7

The correct answer is 1.0x10-7.
3 0
3 years ago
Read 2 more answers
In writing a chemical equation that produces hydrogen gas, the correct representation of hydrogen gas is
Dennis_Churaev [7]

Answer:

h2

Explanation:

5 0
2 years ago
An egg is placed in a graduated cylinder to determine its volume. The following data are obtained. What is the volume of the egg
Natalka [10]

If egg is dipped in cylinder then the volume of egg will be difference in the volumes before dipping egg (initial volume) and volume after dipping egg (final volume)

Volume of egg= 58.5-50.0 = 8.5 mL

7 0
3 years ago
How many moles of water are produced when 5 moles of hydrogen gas react with 2 moles of oxygen gas?
Marysya12 [62]

4 moles of water are produced

Explanation:

  • 4 moles of water are produced when 5 moles of hydrogen is reacted with 2 moles of oxygen gas
  • The balanced equation given is when 2 moles of hydrogen reacts with 1 mole of oxygen and it forms 2 moles of water.
  • The equation we have to solve is the 5 moles of hydrogen is reacting with 2 moles of oxygen gas, we can write the equation as 5H_{2} +2O_{2} -->  4H_{2} O + H_{2}
  • This is the balanced equation when 5 moles of hydrogen reacts with 2 moles of oxygen. The balanced equation means the number of hydrogen atoms and oxygen atoms on both sides would be equal in number.
4 0
3 years ago
Fe(NO3)2 not sure how to get the oxidation numbers of all elements
Cloud [144]
<span>Fe(NO3)2
The NO3 part is a poly-atomic ion with total charge -1.
This is because Fe has a +2 charge and two NO3's with a -1 charge will balance out to 0.
 Most often we just make the assumption that Oxygen has a -2 oxidation number because it is very electro-negative.
So to find N, we just need an oxidation number that balances out with 3(-2) to get -1 (the total charge of the ion)</span>
3 0
2 years ago
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