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3 years ago

Please help i will mark brainlist

Chemistry

2 answers:

Sphinxa [80]3 years ago

4 0

Answer:

V= 21 cubic cm (( I am not sure about density ))

Explanation:

V= L×W×H

Elan Coil [88]3 years ago

4 0

Answer:

volume = 21 cubic cm or 21 cm^3

density = 3 g/cm^3

Explanation:

volume = length × breadth × height

vol = 7 × 3 × 1 = 21 cubic cm

hence, volume = 21 cubic cm.

density = mass / volume

density = 63 / 21 = 3 g / cm^3

i hope it helped. ...

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How many different elements are combined in sulfur dioxide

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Answer: 2elements sulfur and oxygen

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An excess of sodium carbonate, Na, CO3, in solution is added to a solution containing 17.87 g CaCl2. After performing the

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Answer:

Approximately $81.84\%$ .

Explanation:

Balanced equation for this reaction:

${\rm Na_{2}CO_{3}}\, (aq) + {\rm CaCl_{2}} \, (aq) \to 2\; {\rm NaCl}\, (aq) + {\rm CaCO_{3}}\, (s)$ .

Look up the relative atomic mass of elements in the limiting reactant, $\rm CaCl_{2}$ , as well as those in the product of interest, $\rm CaCO_{3}$ :

$\rm Ca$ : $40.078$ .
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$\rm C$ : $12.011$ .
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Calculate the formula mass for both the limiting reactant and the product of interest:

$\begin{aligned}& M({\rm CaCl_{2}}) \\ &= (40.078 + 2 \times 35.45)\; {\rm g \cdot mol^{-1}} \\ &= 110.978\; \rm g \cdot mol^{-1}\end{aligned}$ .

$\begin{aligned}& M({\rm CaCO_{3}}) \\ &= (40.078 + 12.011 + 3 \times 15.999)\; {\rm g \cdot mol^{-1}} \\ &= 100.086\; \rm g \cdot mol^{-1}\end{aligned}$ .

Calculate the quantity of the limiting reactant ( $\rm CaCl_{2}$ ) available to this reaction:

$\begin{aligned}n({\rm CaCl_{2}) &= \frac{m({\rm {CaCl_{2}})}}{M({\rm CaCl_{2}})} \\ &= \frac{17.87\; \rm g}{110.978\; \rm g \cdot mol^{-1}} \\ &\approx 0.161023\; \rm mol \end{aligned}$ .

Refer to the balanced equation for this reaction. The coefficients of the limiting reactant ( $\rm CaCl_{2}$ ) and the product ( ${\rm CaCO_{3}}$ ) are both $1$ . Thus:

$\displaystyle \frac{n({\rm CaCO_{3}})}{n({\rm CaCl_{2}})} = 1$ .

In other words, for every $1\; \rm mol$ of $\rm CaCl_{2}$ formula units that are consumed, $1\; \rm mol\!$ of $\rm CaCO_{3}$ formula units would (in theory) be produced. Thus, calculate the theoretical yield of $\rm CaCO_{3}\!$ in this experiment:

$\begin{aligned} & n(\text{${\rm CaCO_{3}}$, theoretical}) \\ =\; & n({\rm CaCl_{2}}) \cdot \frac{n({\rm CaCO_{3}})}{n({\rm CaCl_{2}})} \\ \approx \; & 0.161023\; {\rm mol} \times 1 \\ =\; & 0.161023\; \rm mol\end{aligned}$ .

Calculate the theoretical yield of this experiment in terms of the mass of $\rm CaCO_{3}$ expected to be produced:

$\begin{aligned} & m(\text{${\rm CaCO_{3}}$, theoretical}) \\ = \; & n(\text{${\rm CaCO_{3}}$, theoretical}) \cdot M(({\rm CaCO_{3}}) \\ \approx \; & 0.161023\; {\rm mol} \times 100.086\; {\rm g \cdot mol^{-1}} \\ \approx \; & 16.1161\; \rm g \end{aligned}$ .

Given that the actual yield in this question (in terms of the mass of $\rm CaCO_{3}$ ) is $13.19\; \rm g$ , calculate the percentage yield of this experiment:

$\begin{aligned} & \text{percentage yield} \\ =\; & \frac{\text{actual yield}}{\text{theoretical yield}} \times 100\% \\ \approx \; & \frac{13.19\; {\rm g}}{16.1161\; {\rm g}} \times 100\% \\ \approx \; & 81.84\%\end{aligned}$ .

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A solution containing 292 g of Mg(NO3)2 per liter has a density of 1.108 g/mL. The molality of the solution is:

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Molality of a solution is defined as the number of moles of solute dissolved per kg of the solvent.

$Molality=\frac{n}{W_s}$

where,

n = moles of solute

$W_s$ = weight of solvent in kg

moles of solute = $\frac{\text {given mass}}{\text {molar mass}}=\frac{292g}{148g/mol}=1.97moles$

volume of solution = 1L = 1000 ml (1L=1000ml)

Mass of solution= ${\text {Density of solution}}\times {\text {Volume of solution}}=1.108g/ml\times 1000ml=1108g$

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mass of solvent = mass of solution - mass of solute = (1108- 292) g = 816g = 0.816 kg

Now put all the given values in the formula of molality, we get

$Molality=\frac{1.97moles}{0.816kg}=2.41mole/kg$

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vladimir1956 [14]

c) The motion of water molecules causes them to leave the liquid and become a gas

Explanation:

When water evaporates, the motion of water molecules causes them to leave the liquid and become a gas. Evaporation is merely a phase change in which liquids changes to solid.

During the process of evaporation, heat energy causes the motion of the particles or molecules to increase.
This will then break the intermolecular forces holding them together leading to more freedom of the molecules.
The molecules will then move from being liquids to solids.

Learn more:

Evaporation brainly.com/question/10972073

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