Which of the following is NOT a clue that a chemical change has occurred? * 1 point Sugar turns blackish-brown as it is heated.
1 answer:
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Answer:
D. -120.9 kJ
Explanation:
According to Hess's law ,the total enthalpy change for a reaction is the sum of all changes regardless of the stages or the steps of the reaction.
....(1)
(this reaction should be reversed in order to reach the required reaction )
On reversing the reaction the sign of get reversed.
(In this case change sign from '-' to'+'. Hence = + 65 kJ)
....(1)
......(2)
Adding equation (1) and (2)
(It is nearly equal to -120.9 kJ)
Answer:
The molar concentration would have to be 0,81 M.
Explanation:
The osmotic pressure equation is:
where:
: osmotic pressure [atm]
M: molar concentration [M]
R: gas constant 0,08205 [atm.L/mol.°K]
T: absolute temperature [°K]
To solve the problem, we just clear M from the osmotic pressure equation and then replace our data using the appropiate units. Clearing the variable M we have:
We have to use temperature as absolute temperature (in kelvins), T=29+273=302 °K. Now we can replace our values in the equation:
As we can see, all units will be simplified and we'll have the molar concentration in mol/L.