What is larger than a galaxy?

Manganese metal can be obtained by the reaction of manganese dioxide with aluminium. 4Al(s) + 3MnOz(s) → 2 Al2O3(s) + 3 Mn(s) Ca

Snezhnost [94]

Answer : The enthalpy change of reaction is -1800 kJ

Explanation :

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.

The given final reaction is,

$4Al(s)+3MnO_2(s)\rightarrow 2Al_2O_3(s)+3Mn(s)$ $\Delta H=?$

The intermediate balanced chemical reaction will be,

(1) $2Al(s)+\frac{3}{2}O_2(g)\rightarrow Al_2O_3(s)$ $\Delta H_1=-1680kJ/mole$

(2) $Mn(s)+O_2(g)\rightarrow MnO_2(s)$ $\Delta H_2=-520kJ/mole$

First we will multiply reaction 1 by 2 and reverse reaction of reaction 2 by 3 then adding both the equation, we get :

The expression for final enthalpy is,

$\Delta H=[n\times \Delta H_1]+[n\times (-\Delta H_2)]$

where,

n = number of moles

$\Delta H=[2mole\times (-1680kJ/mole)]+[3\times -(-520kJ/mole)]$

$\Delta H=-1800kJ$

Therefore, the enthalpy change of reaction is -1800 kJ

8 0

3 years ago

Which of the following is always a reactant in a combustion reaction?

Marina86 [1]

Answer:

Oxygen

Explanation:

Any Hydrocarbon + Oxygen ----> Carbon Dioxide + H2O (Water vapour, gas, water)

5 0

3 years ago

Read 2 more answers

Phenol, c6h5oh, is a stronger acid than methanol, ch3oh, even though both contain an o]h bond. Draw the structures of the anions

timurjin [86]

In resonance structures, the chemical connectivity in the molecule is same but the distribution of electrons are different around the structure. They are created by moving electrons in double or triple bonds, and not atoms.

Phenol, $C_6H_5OH$ and methanol, $CH_3OH$ both are alcohols that contain an $-OH$ group attached to carbon atom.

Due to loss of 1 $H$ from phenol, it forms phenoxide anion and due to presence of double bond in the benzene ring the negative charge on the oxygen atom (which represents electrons) will resonate with double bonds of benzene ring as shown in the image. The resonance-stabilized phenoxide ion is more stable. Whereas when methanol lose 1 $H$ it forms methoxide anion and there are no such electrons present in the structure of methoxide that will result in the movement of electron. Since, due to resonance-stabilized phenoxide ion is more stable than methoxide ion, so it is a stronger acid.