Answer:
Negative
Explanation:
For a solution to form, the change in Gibbs free energy must be negative for dissolving. When a solute dissolves in a saturated solution, ΔH(enthalpy change) is negative and ΔS(entropy change) is positive, giving rise to a large negative ΔG(change in gibbs free energy) and a very high solubility.
Answer:
Percent Yield = 80%
Explanation:
Percent yield of a reaction is defined as one hundred times the ratio between the actual yield and the theoretical yield. That is:
Percent yield = Actual Yield / Theoretical Yield * 100
<em>Where theoretical yield of CaHPO4 is 10g and actual yield is 8g</em>
Replacing:
Percent yield = 8g / 10g * 100
<h3>Percent Yield = 80%</h3>
Is this a question or are you saying thx for the answers
if so np
Im not sure if i answered or not
Answer:
The student conclude that the sample of benzoic acid is impure.
Explanation:
The observed melting point of benzoic acid when a student melts his/her sample is low than the actual value. The reason for this might be:
(a) <u>The most probable reason is that the sample is impure. Impurities in the sample leads to lowering the value of the melting point.</u> The reason for the phenomenon is that when impurity is present in the compound, the pattern of the crystal lattice disturbs and thus it less amount of heat is require to break the lattice.
(b) There may be some experimental errors like:
- Non-uniform heating of the sample
- The sample is not tightly filled in the capillary if the student is following Kjeldahl's flask method.
- If the student is using melting point machine, there there might be some instrumental errors.
<u>The student conclude that the sample is impure.</u>
Answer:
See below.
Explanation:
The mass of octane in the sample of gasoline is 0.02851 * 482.6 = 13.759 g of octane.
The balanced equation is:
2C8H18(l) + 25O2(g) ----> 16CO2(g) + 18H2O(g)
From the equation, using atomic masses:
228.29 g of octane forms 704 g of CO2 and 324.3 g of H2O
So the mass of CO2 formed from the combustion of 13.759 g of octane = (704 * 13.759) / 228.29
= 42.43 g of CO2.
Amount of water = 324.3 * 13.759) / 228.29
= 19.55 g of H2O.