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4 years ago

How is a coefficient used to balance an equation

1 answer:

3 0

Let's start to understand this question by a simple combustion reaction involving oxidation of Ethane in the presence of Oxygen. When Ethane is burned in the presence of Oxygen it produces Carbon Dioxide and Water respectively. Therefore, the equation is as,

C₂H₆ + O₂ → CO₂ + H₂O

Above reaction shows the reaction and the equation is unbalanced. Balancing chemical equation is important because according to law of conservation of mass, mass can neither be created nor destroyed. Hence, we should balance the number of elements on both side.

LHS RHS

Carbon Atoms 2 1

Hydrogen Atoms 6 2

Oxygen Atoms 2 3

It means this equation is not obeying the law. Now, how to balance? One way is as follow,

C₂H₆ + O₃ → C₂O₂ + H₆O

LHS RHS

Carbon Atoms 2 2

Hydrogen Atoms 6 6

Oxygen Atoms 3 3

We have balanced the equation by changing the subscripts. But, we have messed up the chemical composition of compounds and molecules like Oxygen is converted into Ozone.

Therefore, we will change the coefficients (moles) to balance the equation as,

C₂H₆ + 7/2 O₂ → 2 CO₂ + 3 H₂O

LHS RHS

Carbon Atoms 2 2

Hydrogen Atoms 6 6

Oxygen Atoms 7 7

Now, by changing the coefficients we have balanced the equation without disturbing the chemical composition of compounds and molecules.

You might be interested in

What's the amount of solute in 1.75 L of 0.25 M HCl?

Fynjy0 [20]

Answer: 0.4375 mols of solute

Explanation:

The problem is asking for the amount of solute. We are given the value of molarity. The molarity is 0.25M. We know that molarity is $M=\frac{mols of solute}{liters of solution}$ . Since we are given the liters of solution is 1.75, we can use those values to solve for mols of solute.

$0.25M=\frac{x}{1.75L}$ [multiply both sides by 1.75 L]

$x=0.4375 mols$

There are 0.4375 mols of solute.

5 0

4 years ago

Calculate the concentration of acetic acid and acetate ion in a 0.2 M acetate buffer at pH 5. The p K a of acetic acid is 4.76

Levart [38]

Answer:

[Acetic acid] = 0.07 M

[Acetate] = 0.13 M

Explanation:

pH of buffer = 5

pKa of acetic acid = 4.76

$pH=p_{Ka} + log\frac{[Salt]}{[Acid]}$

Now using Henderson-Hasselbalch equation

$5=4.76 + log\frac{[Acetate]}{[Acetic\;acid]}$

$log\frac{[Acetate]}{[Acetic\;acid]} = 0.24$

$\frac{[Acetate]}{[Acetic\;acid]} = 1.74$ ....... (1)

It is given that,

[Acetate] + [Acetic acid] = 0.2 M ....... (2)

Now solving both the above equations

[Acetate] = 1.74[Acetic acid]

Substitute the concentration of acetate ion in equation (2)

1.74[Acetic acid] + [Acetic acid] = 0.2 M

[Acetic acid] = 0.2/2.74 = 0.07 M

[Acetate] = 0.2 - 0.07 = 0.13 M

5 0

3 years ago

Find an expression for the change in entropy when two blocks of the same substance of equal mass, one at the temperature Th and

Gre4nikov [31]

Explanation:

Relation between entropy change and specific heat is as follows.

$\Delta S = C_{p} log (\frac{T_{2}}{T_{1}})$

The given data is as follows.

mass = 500 g, $C_{p}$ = 24.4 J/mol K

$T_{h}$ = 500 K, $T_{c}$ = 250 K

Mass number of copper = 63.54 g /mol

Number of moles = $\frac{mass}{/text{\molar mass}}$

= $\frac{500}{63.54}$

= 7.86 moles

Now, equating the entropy change for both the substances as follows.

$7.86 \times 24.4 \times [T_{f} - 250]$ = $7.86 \times 24.4 \times [500 -T_{f}]$

$T_{f} - 250 = 500 - T_{f}$

$2T_{f}$ = 750

So, $T_{f}$ = $375^{o}C$

For the metal block A, change in entropy is as follows.

$\Delta S = C_{p} log (\frac{T_{2}}{T_{1}})$

= $24.4 log [\frac{375}{500}]$

= -3.04 J/ K mol

For the block B, change in entropy is as follows.

$\Delta S = C_{p} log (\frac{T_{2}}{T_{1}})$

= $24.4 log [\frac{375}{250}]$

= 4.296 J/Kmol

And, total entropy change will be as follows.

= 4.296 + (-3.04)

= 1.256 J/Kmol

Thus, we can conclude that change in entropy of block A is -3.04 J/ K mol and change in entropy of block B is 4.296 J/Kmol.

8 0

3 years ago

Which one of the following hydrocarbons exhibit geometrical isomerism?

denis-greek [22]

the answer is B.2-butene and D.3-hexene

they exhibit geometrical isomerism because they have a double bond that is not marginal

6 0

4 years ago

Read 2 more answers

Match the vocabulary word with its definition. Match the items in the left column to the items in the right column. 1. The actua

tekilochka [14]

Answer:

1. The actual amount of product that is produced from a given amount of reactant or reactants. → actual yield

2. A law which states that in ordinary chemical reactions, the sum of the masses of the reactants always equals the sum of the masses of the products. → Conservation of Mass

3. The reactant that is not used up in a reaction that goes to completion

→ excess reactant

4. The reactant that limits how much product is produced in a reaction that goes to completion. It is used up in the reaction. → limiting reactant

5. The ratio of the actual yield to theoretical yield multiplied times 100.

→ percent yield

6. The maximum calculated amount of product produced from a given reactant in a reaction that goes to completion. → theoretical yield

7. The study of the quantitative relationships between reactants and products in a chemical reaction. → stoichiometry

Explanation:

1. The actual amount of product that is produced from a given amount of reactant or reactants. → actual yield

The actual yield is the actual amount of product that is produced in a chemical reaction and it can be determined experimentally.

2. A law which states that in ordinary chemical reactions, the sum of the masses of the reactants always equals the sum of the masses of the products. → Conservation of Mass

The law of conservation of mass states that mass in an isolated closed system is neither created nor destroyed by chemical reactions or physical transformations. According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants.

3. The reactant that is not used up in a reaction that goes to completion

→ excess reactant

In any chemical reaction between two or more reactants, the excess reactant is the substance that is leftover when the chemical reaction is ended. The amount of product formed is not limited by this reagent.

4. The reactant that limits how much product is produced in a reaction that goes to completion. It is used up in the reaction. → limiting reactant

In any chemical reaction between two or more reactants, the limiting reactant is the substance that is consumed completely when the chemical reaction is ended. The amount of product formed is limited by this reagent, since the reaction cannot continue without it.

5. The ratio of the actual yield to theoretical yield multiplied times 100.

→ percent yield

percent yield = (actual yield / theoretical yield) *100

6. The maximum calculated amount of product produced from a given

reactant in a reaction that goes to completion.

→ theoretical yield

theoretical yield is defined as the amount of the obtained desired product.

7. The study of the quantitative relationships between reactants and products in a chemical reaction.

→ Stoichiometry

Stoichiometry is a branch of chemistry that deals with relationships between reactants and/or products in a reaction to determine desired quantitative data.

3 0

3 years ago