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3 years ago

11

some places such as caves and sinkholes have lower elevations than surrounding areas infer how a sink might be shown on a topogr

aphic map

1 answer:

Andreyy893 years ago

5 0

Answer:

By closed contours with hachures

Explanation:

A sinkhole is a depression in the ground that forms when water erodes an underlying rock layer.

Sinkholes are denoted by closed contours with tick marks (hachures) that point towards lower ground.

The topographical map below shows the difference between the contours of a hill and those of a sinkhole.

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20cm of 0.09M solution of H2SO4. requires 30cm of NaOH for complete neutralization. Calculate the

kirill115 [55]

Answer:

Choice A: approximately $0.12\; \rm M$ .

Explanation:

Note that the unit of concentration, $\rm M$ , typically refers to moles per liter (that is: $1\; \rm M = 1\; \rm mol\cdot L^{-1}$ .)

On the other hand, the volume of the two solutions in this question are apparently given in $\rm cm^3$ , which is the same as $\rm mL$ (that is: $1\; \rm cm^{3} = 1\; \rm mL$ .) Convert the unit of volume to liters:

$V(\mathrm{H_2SO_4}) = 20\; \rm cm^{3} = 20 \times 10^{-3}\; \rm L = 0.02\; \rm L$ .
$V(\mathrm{NaOH}) = 30\; \rm cm^{3} = 30 \times 10^{-3}\; \rm L = 0.03\; \rm L$ .

Calculate the number of moles of $\rm H_2SO_4$ formula units in that $0.02\; \rm L$ of the $0.09\; \rm M$ solution:

$\begin{aligned}n(\mathrm{H_2SO_4}) &= c(\mathrm{H_2SO_4}) \cdot V(\mathrm{H_2SO_4})\\ &= 0.02 \; \rm L \times 0.09 \; \rm mol\cdot L^{-1} = 0.0018\; \rm mol \end{aligned}$ .

Note that $\rm H_2SO_4$ (sulfuric acid) is a diprotic acid. When one mole of $\rm H_2SO_4$ completely dissolves in water, two moles of $\rm H^{+}$ ions will be released.

On the other hand, $\rm NaOH$ (sodium hydroxide) is a monoprotic base. When one mole of $\rm NaOH$ formula units completely dissolve in water, only one mole of $\rm OH^{-}$ ions will be released.

$\rm H^{+}$ ions and $\rm OH^{-}$ ions neutralize each other at a one-to-one ratio. Therefore, when one mole of the diprotic acid $\rm H_2SO_4$ dissolves in water completely, it will take two moles of $\rm OH^{-}$ to neutralize that two moles of $\rm H^{+}$ produced. On the other hand, two moles formula units of the monoprotic base $\rm NaOH$ will be required to produce that two moles of $\rm OH^{-}$ . Therefore, $\rm NaOH$ and $\rm H_2SO_4$ formula units would neutralize each other at a two-to-one ratio.

$\rm H_2SO_4 + 2\; NaOH \to Na_2SO_4 + 2\; H_2O$ .

$\displaystyle \frac{n(\mathrm{NaOH})}{n(\mathrm{H_2SO_4})} = \frac{2}{1} = 2$ .

Previous calculations show that $0.0018\; \rm mol$ of $\rm H_2SO_4$ was produced. Calculate the number of moles of $\rm NaOH$ formula units required to neutralize that

$\begin{aligned}n(\mathrm{NaOH}) &= \frac{n(\mathrm{NaOH})}{n(\mathrm{H_2SO_4})}\cdot n(\mathrm{H_2SO_4}) \\&= 2 \times 0.0018\; \rm mol = 0.0036\; \rm mol\end{aligned}$ .

Calculate the concentration of a $0.03\; \rm L$ solution that contains exactly $0.0036\; \rm mol$ of $\rm NaOH$ formula units:

$\begin{aligned}c(\mathrm{NaOH}) &= \frac{n(\mathrm{NaOH})}{V(\mathrm{NaOH})} = \frac{0.0036\; \rm mol}{0.03\; \rm L} = 0.12\; \rm mol \cdot L^{-1}\end{aligned}$ .

3 0

3 years ago

A gas has experienced a small increase in volume but has maintained the same pressure and number of moles. According to the idea

krek1111 [17]

Answer:

If a gas has experienced a small increase in volume but has maintained the same pressure and number of moles, the temperature of the gas will DROP.

Explanation:

According to Boyle’s law of ideal gases, volume and temperature of a gas is inversely related, as long as the pressure is kept constant;

P₁V₁/T₁ = P₂V₂/T₂

Therefore, if the volume of the gas increases, the temperature will definitely decrease due to the inverse relationship. The gas will get cooler.

Learn More:

For more on Boyle's Law check out;

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brainly.com/question/2568628

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3 years ago

Which chemical equation below is balanced correctly?

Sveta_85 [38]

Al4C3 + 12H2O-----> 3CH4 + 4Al(OH)3

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3 years ago

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What host is used to make the flu vaccine and why can this host be a problem for some people?

valentinak56 [21]

Chicken eggs are used as host and this can be a problem for people with egg allergies!!

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3 years ago

Which of the following statements is true?

Andre45 [30]

"The heat of fusion for a substance is the energy required to change from the vapor to plasma phase."

This I do belive is the answer to the question.

hope it helps.

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3 years ago