Chemistry Urgent Help (1 Viewer)

[Farhanthestudent005]

Will appreciate if I am helped with these questions. Chemistry is highly confusing for me and I am lost. Che

 

[jazz519]

1) find concentration using c = n/v and n = m/MM.

After use c1v1 = c2v2, as a dilution is occurring
This represents concentration of Na2CO3. As each Na2CO3 contains 2Na+, this means the final answer will be c(Na+) = 2 x c(Na2CO3)

2) deltaH = bonds broken - bonds formed

bonds broken is referring to the reactants.
bonds broken = N2 triple bond + 3 H-H
bonds broken = 945 + 3(436) = 2253 kJ/mol

bonds formed is referring to the products.
bonds formed = 2x (3 N-H) = 6 N-H
bonds formed = 6x391 = 2346 kJ/mol

sub those in and you get deltaH = 2253 - 2346 = -93 kJ/mol (which is probably meant to be B, as A and B are both +93 so one of them should've been written as -93)

3) Synthesis reactions are generally defined as when you combine simpler (smaller) molecules to make a complex (larger) molecule. only one that's really doing that is A.

C and D are the opposite of synthesis, which is decomposition - going from more complex to simpler molecules.

 

[CM_Tutor]

For the second question, the answer is there is no correct answer due to a typo

Bonds Broken = 1 x BE(NN) + 3 x BE(H-H) = 945 + 3 x 436 = 2 253 kJ mol^-1

Bonds Formed = 2 x 3 x BE(N-H) = 6 x 391 = 2 346 kJ mol^-1

Sine bond breaking requires energy (endothermic) and bond formation releases energy (exothermic)

= 2 253 + -2346 = -93 kJ mol^-1

I think (B) is meant to be this answer but the minus is missing... otherwise, (A) and (B) are identical.

 

[wendyredvelvet]

GUYSS.. ARE YOU ABLE TO HELP ME TOOO.. PLEASE
Hey,
Are you able to help me with the following problem:

What structural information about caffeine does the IR spectrum give you? Using the following graph
Are you able to break down the graph and pinpoint the structural info it gives you.. PLEASEEE
Greatly be appreciated if you are able to help with this qn

 

[stressedessert04]

if anyone could provide key notes so i could check my answer is somewhat correct? (3 marks)

 

[jimmysmith560]

if anyone could provide key notes so i could check my answer is somewhat correct? (3 marks)

Would the following sample response help?

The usefulness of an indicator is dependent on its accuracy and its effectiveness. The accuracy of an indicator refers to how narrow the pH colour change range is (the narrower it is the more accurate the indicator is). The indicator's effectiveness is dependent on where on the pH scale it lies. Hence, an indicator that changes colour in the acidic region is most effective for strong acid weak base titrations whose equivalence point is below 7.

The accuracy of this indicator is unable to be calculated from the results. Further testing is required to determine how narrow the pH range is, however, the colour change range occurs near the pH of lemon juice.

The effectiveness of this indicator can be seen due to it changing colour in the acidic region. Hence, it is effective for strong acid weak base titrations.

The usefulness of the yellow flower indicator is relatively high for strong acid weak base titrations assuming that it has a narrow and precise colour change range for accuracy. However, if its colour change range was very wide, it would not be useful for titrations as there would be a large gap between the equivalence and endpoint of a reaction.