Question

Which of these reactions are exothermic?

3 C(s) + 4 H2(g) → C3H8(g) ΔH = -103.8 kJ

C(s) + O2(g) → CO2(g) ΔH = -393.5 kJ

H2(g) + 1/2 O2(g) → H2O(g) ΔH = -241.8 kJ

Cl3PO(g) → PCl3(g) + 1/2 O2(g) ΔH = +285.7 kJ
@Somy
@Abhisar
@Abmon98

Answer 1

Negative sign shows that reaction is Exothermic
Positive sign shows that reaction is Endothermic

Answer 2

so it a ,b or c is that what you telling me ? @Somy

Answer 3

yes A, B and C

Answer 4

do u understand the difference between Exo and Endo reactions?

Answer 5

yes it just the formula that get me all u know @Somy

Answer 6

it a mutiple question so i click all three lol @Somy

Answer 7

it did say choose the ones that are Exo lol

Answer 8

Which of these reactions are exothermic?
'are'
which means there are more than 1 answers lol

Answer 9

yes@ somy lol o hate theses test

Answer 10

ikr <.< just condition 'test' makes me stupid and i forget everything hhh

Answer 11

If the reaction is reversed during a Hess’s law calculation, what must be done to the ΔH for that reaction?

It must be left alone.

It must be multiplied by 1.

The sign must change.

The sign must not change.
@Somy

Answer 12

its reversed so Sign must change right?

Answer 13

that what i was thinking?

Answer 14

i mean if you want to melt something
you give heat thus " + "
but now you want it back to original form so you freeze it -reverse reaction
so that means you take back that energy you gave
so sign is now ' - '

Answer 15

ok cool lol @Somy

Answer 16

thank you @Somy

Answer 17

:)