What always happens during a chemical change?

1 answer:

7 0

In a chemical change, the atoms in the reactants rearrange themselves and bond together differently to form one or more new products with different characteristics than the reactants. When a new substance is formed, the change is called a chemical change.

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A 10.0 mL sample of HNO3 was exactly neutralized by 13.5 mL of 1.0 M KOH. What is the molarity of the HNO3? Use the titrations f

Kruka [31]

Answer: Thus molarity of $HNO_3$ is 1.35 M

Explanation:

To calculate the volume of acid, we use the equation given by neutralization reaction:

$n_1M_1V_1=n_2M_2V_2$

where,

$n_1,M_1\text{ and }V_1$ are the n-factor, molarity and volume of acid which is $HNO_3$

$n_2,M_2\text{ and }V_2$ are the n-factor, molarity and volume of base which is KOH.

We are given:

$n_1=1\\M_1=?M\\V_1=10.0mL\\n_2=1\\M_2=1.0M\\V_2=13.5mL$

Putting values in above equation, we get:

$1\times M_1\times 10.0=1\times 1.0\times 13.5\\\\M_1=1.35M$

Thus molarity of $HNO_3$ is 1.35 M

7 0

3 years ago

Which of the following elements listed is the least metallic

Dominik [7]

Where's the list? It depends on which one it is. It could be Chlorine, silicon, or anything on the non metals side of the periodic table if you don't list it.

5 0

4 years ago

What substance would you add to KF(aq) to form a buffer solution? View Available Hint(s) What substance would you add to to form

AnnyKZ [126]

<h3>Answer</h3>

<h3>Explanation</h3>

A buffer solution contains <em>a weak acid</em> and<em> its conjugate base</em>. The two species shall have a similar concentration in the solution. It's also possible for <em>a weak base</em> and <em>its conjugate acid</em> to form a buffer solution.

The KF solution already contains large number of $\text{F}^{-}$ ions. The objective is to thus find its conjugate acid or base.

$\text{F}^{-}$ contains no proton $\text{H}^{+}$ and is unlikely to be a conjugate acid. Assuming that $\text{F}^{-}$ is a conjugate base. Adding one proton to $\text{F}^{-}$ would produce its conjugate acid.

$\text{H}^{+} \; (aq) + \text{F}^{-} \; (aq) \rightleftharpoons \text{HF}\; (aq)$

Therefore $\text{HF}$ is the conjugate acid of $\text{F}^{-}$ . $\text{HF}$ happens to be a weak acid. As a result, combining $\text{F}^{-}$ with $\text{HF}$ would produce a solution with large number of both the weak acid and its conjugate base, which is a buffer solution by definition.