A child’s bike containing 5.25 kg of iron rusts according to the thermochemical equation shown here:

Element 2 is:<br> A) Cobalt<br> B)Chlorine <br> C)Calcium<br> D)Carbon

saul85 [17]

Answer:

D: Carbon

Explanation:

Carbon is the sixth element with a total of 6 electrons in the periodic table. Hence the atomic number Z = 6. The ground state electron configuration of carbon is 1s2 2s2 2p2. An excited state electron configuration of carbon is 1s2 2s1 2p3.

4 0

3 years ago

A strontium hydroxide solution is prepared by dissolving 10.60 gg of Sr(OH)2Sr(OH)2 in water to make 47.00 mLmL of solution.What

NeTakaya

Answer:

Approximately $1.854\; \rm mol\cdot L^{-1}$ .

Explanation:

Note that both figures in the question come with four significant figures. Therefore, the answer should also be rounded to four significant figures. Intermediate results should have more significant figures than that.

<h3>Formula mass of strontium hydroxide</h3>

Look up the relative atomic mass of $\rm Sr$ , $\rm O$ , and $\rm H$ on a modern periodic table. Keep at least four significant figures in each of these atomic mass data.

$\rm Sr$ : $87.62$ .
$\rm O$ : $15.999$ .
$\rm H$ : $1.008$ .

Calculate the formula mass of $\rm Sr(OH)_2$ :

$M\left(\rm Sr(OH)_2\right) = 87.62 + 2\times (15.999 + 1.008) = 121.634\; \rm g \cdot mol^{-1}$ .

<h3>Number of moles of strontium hydroxide in the solution</h3>

$M\left(\rm Sr(OH)_2\right) =121.634\; \rm g \cdot mol^{-1}$ means that each mole of $\rm Sr(OH)_2$ formula units have a mass of $121.634\; \rm g$ .

The question states that there are $10.60\; \rm g$ of $\rm Sr(OH)_2$ in this solution.

How many moles of $\rm Sr(OH)_2$ formula units would that be?

$\begin{aligned}n\left(\rm Sr(OH)_2\right) &= \frac{m\left(\rm Sr(OH)_2\right)}{M\left(\rm Sr(OH)_2\right)}\\ &= \frac{10.60\; \rm g}{121.634\; \rm g \cdot mol^{-1}} \approx 8.71467\times 10^{-2}\; \rm mol\end{aligned}$ .

<h3>Molarity of this strontium hydroxide solution</h3>

There are $8.71467\times 10^{-2}\; \rm mol$ of $\rm Sr(OH)_2$ formula units in this $47\; \rm mL$ solution. Convert the unit of volume to liter:

$V = 47\; \rm mL = 0.047\; \rm L$ .

The molarity of a solution measures its molar concentration. For this solution:

$\begin{aligned}c\left(\rm Sr(OH)_2\right) &= \frac{n\left(\rm Sr(OH)_2\right)}{V}\\ &= \frac{8.71467\times 10^{-2}\; \rm mol}{0.047\; \rm L} \approx 1.854\; \rm mol \cdot L^{-1}\end{aligned}$ .

(Rounded to four significant figures.)

5 0

3 years ago

Which of these is the lowest subgroup? kingdom, order, genus, or species.

olga55 [171]

The correct answer is species

6 0

3 years ago

Read 2 more answers

Calculate the pressure exerted by an book of mass 20kg occupying an area of 2 m square.

kotykmax [81]

The answer is 100 Pa.

The formula for calculating pressure is :

<u>Pressure = Force ÷ Area</u>

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We are given that :

mass = 20 kg
area = 2 m²

We also know that :

<u>Force = mass ×g</u>

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So, force will be :

F = 20 × 10
F = 200 N

Now, we can finally calculate pressure :

P = 200 ÷ 2
P = 100 Pa

8 0

1 year ago

When iodobenzene codistills with water at 760 toor, the boiling point of the mixture is 98.5. the vapor pressure of water is?

katrin [286]

<span>This was one of the old regents. I didn't get this at first glance too so I searched for it and I got this site. lol. I know what to do now. To get a higher boiling point, you have to find which solution has the most moles. Since SO4, PO4, and NO3 are all polyatomic ions, they only count as one mole. </span>

6 0

3 years ago