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3 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]3 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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Suppose a 0.025M aqueous solution of sulfuric acid (H2SO4) is prepared. Calculate the equilibrium molarity of SO4−2. You'll find

FromTheMoon [43]

Answer: The concentration of $SO_4^{2-}$ at equilibrium is 0.00608 M

Explanation:

As, sulfuric acid is a strong acid. So, its first dissociation will easily be done as the first dissociation constant is higher than the second dissociation constant.

In the second dissociation, the ions will remain in equilibrium.

We are given:

Concentration of sulfuric acid = 0.025 M

Equation for the first dissociation of sulfuric acid:

$H_2SO_4(aq.)\rightarrow H^+(aq.)+HSO_4^-(aq.)$

0.025 0.025 0.025

Equation for the second dissociation of sulfuric acid:

$HSO_4^-(aq.)\rightarrow H^+(aq.)+SO_4^{2-}(aq.)$

Initial: 0.025 0.025

At eqllm: 0.025-x 0.025+x x

The expression of second equilibrium constant equation follows:

$Ka_2=\frac{[H^+][SO_4^{2-}]}{[HSO_4^-]}$

We know that:

$Ka_2\text{ for }H_2SO_4=0.01$

Putting values in above equation, we get:

$0.01=\frac{(0.025+x)\times x}{(0.025-x)}\\\\x=-0.0411,0.00608$

Neglecting the negative value of 'x', because concentration cannot be negative.

So, equilibrium concentration of sulfate ion = x = 0.00608 M

Hence, the concentration of $SO_4^{2-}$ at equilibrium is 0.00608 M

4 0

3 years ago

How many theoretical plates produce a chromatography peak eluting at 12.83 min with a width at half-height of 8.7 s

GrogVix [38]

Answer-Figure P38.63a
is a three-dimensional sketch of a birefringent crystal. The dotted lines illustrate how a thin, parallefaced slab of material could be cut from the larger specimen with the crystal’s optic axis parallel to the faces of the plate.”

Sorry if it’s it correct

4 0

2 years ago

Explain why 0.76 * 103 would not be considered a correct answer for a scientific notation problem? What should be done to fix th

Valentin [98]

The decimal should be after the 7 and before the 6.

7 0

3 years ago

Read 2 more answers

Explain why the quantum number set (3, 2, 3, -½) is not possible for an electron in an atom

Triss [41]

Ok the ML (the 3rd number) is not legit because the ML value can only be from -L to L (the second value)

7 0