Since you didn't give the actual volume (or any of the experimental values) I can only tell you how to do it. Do the calculation using the real (determined) volume of the flask. Then, re-do the calculation with v = 125ml. Take the two values and calculate % error; m = measured vol; g = guessed vol.
<span>[mW (m) - mW (g)]/mW (m) x 100% </span>
<span>(they want % error so, if it is negative, just get rid of the sign) </span>
Given :
Number of molecules of hydrogen peroxide, N = 4.5 × 10²².
To Find :
The mass of given molecules of hydrogen peroxide.
Solution :
We know, 1 mole of every compound contains Nₐ = 6.022 × 10²³ molecules.
So, number of moles of hydrogen peroxide is :
Now, mass of hydrogen peroxide is given as :
m = n × M.M
m = 0.0747 × 34 grams
m = 2.54 grams
Hence, this is the required solution.
2.0 L
The key to any dilution calculation is the dilution factor
The dilution factor essentially tells you how concentrated the stock solution was compared with the diluted solution.
In your case, the dilution must take you from a concentrated hydrochloric acid solution of 18.5 M to a diluted solution of 1.5 M, so the dilution factor must be equal to
DF=18.5M1.5M=12.333
So, in order to decrease the concentration of the stock solution by a factor of 12.333, you must increase its volume by a factor of 12.333by adding water.
The volume of the stock solution needed for this dilution will be
DF=VdilutedVstock⇒Vstock=VdilutedDF
Plug in your values to find
Vstock=25.0 L12.333=2.0 L−−−−−
The answer is rounded to two sig figs, the number of significant figures you have for the concentration od the diluted solution.
So, to make 25.0 L of 1.5 M hydrochloric acid solution, take 2.0 L of 18.5 M hydrochloric acid solution and dilute it to a final volume of 25.0 L.
IMPORTANT NOTE! Do not forget that you must always add concentrated acid to water and not the other way around!
In this case, you're working with very concentrated hydrochloric acid, so it would be best to keep the stock solution and the water needed for the dilution in an ice bath before the dilution.
Also, it would be best to perform the dilution in several steps using smaller doses of stock solution. Don't forget to stir as you're adding the acid!
So, to dilute your solution, take several steps to add the concentrated acid solution to enough water to ensure that the final is as close to 25.0 L as possible. If you're still a couple of milliliters short of the target volume, finish the dilution by adding water.
Always remember
Water to concentrated acid →.NO!
Concentrated acid to water →.YES!
<h3>
Answer:</h3>
True, the reaction given is an example of a synthesis reaction
<h3>
Explanation:</h3>
- Synthesis reactions are reactions where two or more substances combine to form a single compound.
- The reaction 2NO(g) + O₂(g) → 2NO₂(g) is an example of a synthesis reaction.
Other types of chemical reactions may include;
- Decomposition reaction in which a compound is broken down into smaller compounds or individual elements.
- Replacement reaction where reactive elements replace other less reactive elements in their salts.
- Precipitation reactions in which soluble salts reacts to form a precipitate and a soluble salt as a result of exchange of anions and cations.
