How many atoms are in 12 moles of I. Check your significant figures.

Calculate ΔH∘f (in kilojoules per mole) for benzene, C6H6, from the following data: 2C6H6(l) + 15O2(g)→12CO2(g)+6H2O(l) ΔH∘=−653

Pachacha [2.7K]

Answer: 48.6 kJ/mol

Explanation:

The balanced chemical reaction is,

$2C_6H_6(l)+15O_2(g)\rightarrow 12CO_2(g)+6H_2O(l)$

The expression for enthalpy change is,

$\Delta H=\sum [n\times \Delta H_f(product)]-\sum [n\times \Delta H_f(reactant)]$

$\Delta H=[(n_{CO_2}\times \Delta H_{CO_2})+(n_{H_2O}\times \Delta H_{H_2O})]-[(n_{O_2}\times \Delta H_{O_2})+(n_{C_6H_6}\times \Delta H_{C_6H_6})]$

where,

n = number of moles

$\Delta H_{O_2}=0$ (as heat of formation of substances in their standard state is zero

Now put all the given values in this expression, we get

$-6534.0=[(12\times -393.5)+(6\times -285.8)]-[(15\times 0)+(2\times \Delta H_{C_6H_6})]$

$\Delta H_{C_6H_6}=48.6kJ/mol$

Therefore, the enthalpy change for benzene is 48.6 kJ/mol

4 0

3 years ago

How do i find a ionic formula? <br><br>for example Ca2+ & S2-

jeka94

Example #1 write the chemical formula for Calcium Oxide

Step 1

-Find the Atomic symbol of the metal and non-metal on the periodic table

CaO

Step 2

Find the charges for Calcium and Oxygen

which are Ca 2+ and O 2-

Step 3

Balance out the charges

They are already balanced out

Here´s the chemical formula for Calcium Oxide

CaO

Example 2 write the chemical formula for Aluminum Oxide

Step 1

-Find the Atomic symbol of the metal and non-metal on the periodic table

A

l

O

Step 2

Find the charges for Aluminum and Oxygen

Which are Al 3+ and O 2-

Step 3

Balance out the charges

You need 2 Aluminum and 3 Oxygen to balance the charges

Al 3+ O 2-

= 6 + O 2-

= 6-

Step 4

If you need more then one element to balance out the charges you identify that by using subscripts

Heres your chemical formula for Aluminum Oxide

$Al_{2} O_{3}$

8 0

3 years ago

What are the names of the following three compounds (see attached)

balu736 [363]

Answer:

1. 4-ethyl-1-heptene

2. 6-ethyl-2-octene

3. 1-butyne

Explanation:

The compounds are named according to IUPAC rules.

Compound 1:

Identify the longest carbon chain. This chain is called the parent chain.
Identify all of the substituents (groups appending from the parent chain).
The parent chain is numbered so that the multiple bonds have the lowest numbers (double has the priority over alkyl substituents).
The longest chain contains 7 carbon atoms, so taken the name hept.
The double bond between C1 and C2, so take no. 1 and add the suffix ene to hept "1-heptene".
The ethyl group is the alkyl substituent on position 4.
So the name is 4-ethyl-1-heptene.

Compound 2:

Identify the longest carbon chain. This chain is called the parent chain.
Identify all of the substituents (groups appending from the parent chain).
The parent chain is numbered so that the multiple bonds have the lowest numbers (double has the priority over alkyl substituents).
The longest chain contains 8 carbon atoms, so taken the name oct.
The double bond between C2 and C3, so take no. 2 and add the suffix ene to oct "2-octene".
The ethyl group is the alkyl substituent on position 6.

So the name is 6-ethyl-2-octene.

Compound 3:

Identify the longest carbon chain. This chain is called the parent chain.
Identify all of the substituents (groups appending from the parent chain), there is no substituents.
The parent chain is numbered so that the multiple bonds have the lowest numbers (Triple bond here take the lowest number).
The longest chain contains 4 carbon atoms, so taken the name but.
The triple bond between C1 and C2, so take no. 1 and add the suffix yne to but "1-butyne".