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4 years ago

Why do we need to balance chemical equations?

2 answers:

8 0

So we know the number of moles of each compound. If we need to know the concentration we must know the number of moles that the compounds react with...

GrogVix [38]4 years ago

6 0

The law of conservation of mass states that matter can neither be created nor destroyed, and it just transforms from one medium to another. Therefore, when a chemical reaction occurs, we need to balance the equation to ensure that the number of particles of the reactants are equal to the number of particles of the products.

Consider the following (unbalanced) equation:
H2 + O2 -> H2O
If this is what actually happens, then where is the second atom of Oxygen?

To ensure that stuff like this doesn't happen, we have to balance equations:
2H2 +O2 -> 2H2O

Now if you count the atoms, you have 4 Hydrogen atoms and 2 Oxygen atoms on both sides, and conservation of mass takes place.

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An example of an extensive property of matter is

timurjin [86]

An example of an extensive property of matter is "mass"

6 0

3 years ago

Read 2 more answers

The AE of a system that releases 12.4 J of heat and does 4.2 J of work on its surroundings It is_______ jA. 16.6 B. 12.4 C. 4.2

andre [41]

ANSWER

EXPLANATION

Given that

The energy released by the system is 12.4J

Work done on the surrounding is 4.2J

Follow the steps below to find the change in energy

In the given data, energy is said to be released to the surroundings

Recall, that exothermic reaction is a type of reaction in which heat is released to the surroundings. Hence, change in enthalpy is negative

Step 1; Write the formula for calculating change in energy

$\Delta E\text{ }=\text{ q }+\text{ w}$

Since heat is released to the surrounding, then q = -12J

Recall, that work done by the system on the surroundings is always negative

Hence, w = -4.2J

Step 2; Substitute the given data into the formula in step 1

$\begin{gathered} \text{ }\Delta E\text{ = q + w} \\ \text{ }\Delta E\text{ }=\text{ -12.4 }+\text{ \lparen-4.2\rparen} \\ \text{ }\Delta E\text{ = -12.4 - 4.2} \\ \text{ }\Delta E\text{ }=\text{ -16.6J} \end{gathered}$

Therefore, the change i

3 0

1 year ago

If a gas sample has a pressure of 30.7 kPa at 0.00*C, by how much does the temperature have to decrease to lower the pressure to

Scrat [10]

Answer:

252.68 K or -20.46 °C

Explanation:

According to Gay-Lussac's Law, "Pressure and Temperature at given volume are directly proportional to each other".

Mathematically,

P₁ / T₁ = P₂ / T₂ ---- (1)

Data Given:

P₁ = 30.7 kPa

T₁ = 0.00 °C = 273.15 K

P₂ = 28.4 kPa

T₂ = <u>???</u>

Solving equation for T₂,

T₂ = P₂ T₁ / P₁

Putting values,

T₂ = 28.4 kPa × 273.15 K / 30.7 kPa

T₂ = 252.68 K or -20.46 °C

8 0

3 years ago

How many moles are in 2.12g Cr2O3

ohaa [14]

Answer:

0.01395mol Cr2O3

Explanation:

the molar mass of Cr2O3 is 151.9904 g/mol

2.12g Cr2O3 x 1 mol/151.9904g = 0.01395mol Cr2O3

4 0

3 years ago

Write and balance the half-reaction for the oxidation of white phosphorous P4 to the phosphate ion PO3^−4 in a basic solution.

aalyn [17]

Since the half-reaction is occurring in a basic solution, add 32OH− to each side of the equation to eliminate the H+ ions.

P₄ +16H₂O + 32OH⁻ ⟶ 4PO₃⁻⁴ + 32H⁺ +32OH⁻

Final reaction :

P₄ + 32OH⁻ ⟶ 4PO₃⁻⁴ + 16H₂O + 20e⁻

A half reaction is either the oxidation or reduction reaction component of a redox reaction. A half reaction is obtained by considering the change in oxidation states of individual substances involved in the redox reaction.

The concept of half-reactions is used to describe what occurs in an electrochemical cell, such as a Galvanic cell battery. Half-reactions can be written to describe both the metal undergoing oxidation (known as the anode) and the metal undergoing reduction (known as the cathode).

Half-reactions are often used as a method of balancing redox reactions. For oxidation-reduction reactions in acidic conditions, after balancing the atoms and oxidation numbers, one will need to add H+ ions to balance the hydrogen ions in the half reaction.

For oxidation-reduction reactions in basic conditions, after balancing the atoms and oxidation numbers, first treat it as an acidic solution and then add OH- ions to balance the H+ ions in the half reactions (which would give H2O).

Learn more about Half reactions here : brainly.com/question/2491738

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3 0

2 years ago