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3 years ago

50 extra if correct !!

Chemistry

1 answer:

leva [86]3 years ago

7 0

Answer:

Explanation:

the gradual movement of the continents across the earth's surface through geological time.

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The flask contains 10.0 mL of HCl and a few drops of phenolphthalein indicator. The buret contains 0.160 M NaOH. It requires 18.

olchik [2.2K]

Answer:

Approximately $0.291\; \rm M$ (rounded to two significant figures.)

Explanation:

The unit of concentration $\rm M$ is the same as $\rm mol \cdot L^{-1}$ (moles per liter.) On the other hand, the volume of both the $\rm NaOH$ solution and the original $\rm HCl$ solution here are in milliliters. Convert these two volumes to liters:

$V(\mathrm{NaOH}) = 18.2\; \rm mL = 18.2 \times 10^{-3}\; \rm L = 0.0182\; \rm L$ .
$V(\text{$\mathrm{HCl}$, original}) = 10.0\; \rm mL = 10.0\times 10^{-3}\; \rm L = 0.0100\; \rm L$ .

Calculate the number of moles of $\rm NaOH$ in that $0.0182\; \rm L$ of $0.160\; \rm M$ solution:

$\begin{aligned} n(\mathrm{NaOH}) &= c(\mathrm{NaOH})\cdot V(\mathrm{NaOH})\\ &= 0.160\; \rm mol \cdot L^{-1} \times 0.0182\; \rm L \approx 0.00291\; \rm mol\end{aligned}$ .

$\rm HCl$ reacts with $\rm NaOH$ at a one-to-one ratio:

$\rm HCl\; (aq) + NaOH\; (aq) \to NaCl\; (aq) + H_2O\; (l)$ .

Coefficient ratio:

$\displaystyle \frac{n(\mathrm{HCl})}{n(\mathrm{NaOH})} = 1$ .

In other words, one mole of $\rm NaOH$ would neutralize exactly one mole of $\rm HCl$ . In this titration, $0.291\; \rm mol$ of $\rm NaOH\!$ was required. Therefore, the same amount of $\rm HC$ should be present in the original solution:

$\begin{aligned}&n(\text{$\mathrm{HCl}$, original})\\ &= n(\mathrm{NaOH})\cdot \frac{n(\mathrm{HCl})}{n(\mathrm{NaOH})} \\ &\approx 0.00291\; \rm mol \times 1 = 0.00291\; \rm mol\end{aligned}$ .

Calculate the concentration of the original $\rm HCl$ solution:

$\displaystyle c(\text{$\mathrm{HCl}$, original}) = \frac{n(\text{$\mathrm{HCl}$, original})}{V(\text{$\mathrm{HCl}$, original})} \approx \frac{0.00291\; \rm mol}{0.0100\; \rm L} \approx 0.291\; \rm M$ .

5 0

3 years ago

2NaCl + F2 yields 2NaF + Cl2

bearhunter [10]

Study your experiment setup. In 30 minutes, how will the air temperature in the bottles compare? What do you predict will happen to the ice in each bottle?

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3 years ago

4Al(s) + 30₂(g) → 2Al2O3 (s)

Margaret [11]

1) 1 molecules
2) 2 oxygen atoms
3)2 moles of Al2O3 are formed
4)4:3

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2 years ago

If a substance cannot be broken down chemically into a simpler substance what is it

Vikentia [17]

Answer: An Element

Explanation:

An element is a substance that cannot be split into smaller substance. It is made up of one kind of atom and can exist either as molecules (e.g nitogen) or an atom (e.g argon).

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3 years ago

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Which statement is a valid conclusion about the activation energy of the reverse reaction if the forward reaction is exothermic?

babunello [35]

Answer:

e) The activation energy of the reverse reaction is greater than that of the forward reaction.

Explanation:

Activation energy is the minimum amount of energy that is required by the reactants to start a reaction.
An exothermic reaction is a reaction that releases heat energy to the surrounding while an endothermic reactions is a reaction that absorbs heat from the surrounding.
In reversible reactions, when the forward reaction is exothermic it means the reverse reaction will be endothermic, therefore the reverse reaction will have a higher activation energy than the forward reaction. The activation energy of the reverse reaction will be the sum of the enthalpy and the activation energy of the forward reaction.

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4 years ago