All categories

4 years ago

How much heat is given off when 8 g of hydrogen reacts in: 2H₂ + O₂ → 2H₂O; ΔH = -115.60 kcal

1 answer:

4 0

ΔΗ= -115.6 kJ/mol
H2 has a Mr of 2, so as mol=mass/mr we can work out that there are 4 moles of H reacting

Therefore we multiply -115.6 by 4 = -462.4

You might be interested in

The balanced combustion reaction for C6H6 is 2C6H6(l)+15O2(g)⟶12CO2(g)+6H2O(l)+6542 kJ If 8.600 g C6H6 is burned and the heat pr

jenyasd209 [6]

Answer : The final temperature of the water is, $22.5166^oC$

Explanation : Given,

Mass of benzene = 8.600 g

Molar mass of benzene = 78 g/mole

First we have to calculate the moles of benzene.

$\text{Moles of benzene}=\frac{\text{Mass of benzene}}{\text{Molar mass of benzene}}=\frac{8.600g}{78g/mol}=0.1103mole$

Now we have to calculate the energy of combustion.

The given balanced chemical reaction is:

$2C_6H_6(l)+15O_2(g)\rightarrow 12CO_2(g)+6H_2O(l)+6542 kJ$

According to reaction,

As, 2 moles of benzene gives 6542 kJ of energy on combustion.

So, 0.1103 mole of benzene gives $\frac{6542 kJ}{2}\times 0.1103=360.7913kJ$ of energy on combustion.

Now we have to calculate the final temperature of the water.

Formula used : $q_w=m_w\times c_w\times \Delta T=m_w\times c_w\times (T_{final}-T_{initial})$

where,

$q_w$ = heat released = 360.7913 kJ = 36079.13 J

$m_w$ = mass of water = 5691 g

$c_w$ = specific heat of water= $4.18J/g^oC$

$T_{final}$ = final temperature = ?

$T_{initial}$ = initial temperature = $21^oC$

Now put all the given values in the above formula, we get:

$36079.13J=5691g\times 4.18J/g^oC\times (T_{final}-21^oC)$

$T_{final}=22.5166^oC$

Therefore, the final temperature of the water is, $22.5166^oC$

8 0

4 years ago

Which carbonate is most stable to heat?

d1i1m1o1n [39]

Answer:

Explanation:

bevxjs zkbxkxbxo xkd ksbslbsi ixbxksbzo

3 0

3 years ago

Read 2 more answers

How many grams are in 2.94 x 1017 atoms of Iron?

ale4655 [162]

Answer:

8.677

⋅

Explanation:

5 0

3 years ago

Archy [21]

Answer:

Pressure

Explanation:

The variable that describes how often the particles in a sample of gas collides with each other and the walls of the container is the pressure.

The pressure of a gas is the combined force with which the gas molecules bombard a unit area of the wall of the container i.e the sum of all the tiny pushes on the unit area of the wall of the container.

The various units of gas pressure atmosphere, millimeters of Hg, torr, pascal, newton per meter squared.

Temperature is the degree of hotness or coldness of a body
Volume is the space the gases occupies.

3 0

3 years ago

A 0.100 M oxalic acid, HO2CCO2H, solution is titrated with 0.100 M KOH. Calculate the pH when 25.00 mL of oxalic acid solution i

____ [38]

Answer:

pH = 4.09

Explanation:

molarity of oxalic acid in the solution

= 0.1 x 25 / (25 + 35)

= 0.0417 M

molarity of NaOH in the solution

= 0.1 x 35 / (25 +35)

= 0.0583 M

H2C2O4 + NaOH -------------------> NaHC2O4 + H2O

0.0417 0.0583 0 0

0 0.0166 0.0417

now second acid -base titration

NaHC2O4 + NaOH -------------------> Na2C2O4 + H2O

0.0417 0.0166 0 0

0.0251 0 0.0166 ---

now

pH = pKa2 + log [Na2C2O4 / NaHC2O4]

pH = 4.27 + log (0.0166 / 0.0251)

pH = 4.09

3 0

3 years ago