CHEMISTRY
MIDDLE SCHOOL

Copernicus

Democritis

Answer: Democritus said that everything in the universe is made up of tiny particles called atoms ......

COLLEGE

Balance the equation and show the calculation of the number of moles and grams of Ca3(PO42 formed from 10.8 grams of Ca(OH)2. Show your answers to 3 significant figures Ca(OH)2 H3PO4-- Ca3(PO4)2 + H2O]

Answer:

The number of moles of calcium phosphate is 0.0485 mol. The mass is 15.1 g.

Explanation:

The balanced equation is:

Ca_{3}(PO_{4})_{2} + 6H_{2}O" alt="3 Ca(OH)_{2} + 2 H_{3}PO_{4} => Ca_{3}(PO_{4})_{2} + 6H_{2}O" align="absmiddle" class="latex-formula">

As we can see, 3 moles of calcium hidroxide produced 1 mol of calcium phosphate. So the quantity of moles of Calcium posphate is:

The mass of calcium phosphate in grams is:

HIGH SCHOOL

The atomic mass of chlorine is listed as 35.454 amu on the periodic table. It has two naturally occurring isotopes, Cl-35 and Cl-37. What are the approximate percentages of each?

X=percentage of Cl-35

(1-x)=percentage of Cl-35

35(x)+37(1-x)=35.454

35x+37-37x=35.454

-2x=35.454-37

-2x=-1.546

x=-1.546/(-2)

x=0.773

0.773=77.3/100=77.3%

(1-x)=1-0.773=0.227

0.227=22.7/100=22.7%

answer: the percentages are: 77.3% of Cl-35 and 22.7% of Cl-37.

(1-x)=percentage of Cl-35

35(x)+37(1-x)=35.454

35x+37-37x=35.454

-2x=35.454-37

-2x=-1.546

x=-1.546/(-2)

x=0.773

0.773=77.3/100=77.3%

(1-x)=1-0.773=0.227

0.227=22.7/100=22.7%

answer: the percentages are: 77.3% of Cl-35 and 22.7% of Cl-37.

COLLEGE

What is the mass of 1.70 moles of magnesium chloride, MgCl2?

162 grams First, look up the atomic weight of all involved elements Atomic weight Magnesium = 24.305 Atomic weight Chlorine = 35.453 Now, calculate the molar mass of MgCl2 24.305 + 2 * 35.453 = 95.211 g/mol Finally, multiply the molar mass by the number of moles 95.211 g/mol * 1.70 mol = 161.8587 g Rounding to 3 significant figures gives 162 grams.

HIGH SCHOOL

Explain two ways that voltaic cells and electrolytic cells are similar AND two ways that they differ.

Similarities:

•They both have cathode and anode charges.

•Cathode facilitates oxidation and the anode facilitates reduction.

Differences:

•Voltaic cells “work” autonomously, while electrolytic cells need an outside source of energy to work.

•While the voltaic cells’ redox reaction is uncalled-for, the electrolytic cells happen at a set time.

I hope I helped!

Chemistry is pretty hard to explain, so feel free to message me or leave a comment below if you need me to elaborate on my response. :)

•They both have cathode and anode charges.

•Cathode facilitates oxidation and the anode facilitates reduction.

Differences:

•Voltaic cells “work” autonomously, while electrolytic cells need an outside source of energy to work.

•While the voltaic cells’ redox reaction is uncalled-for, the electrolytic cells happen at a set time.

I hope I helped!

Chemistry is pretty hard to explain, so feel free to message me or leave a comment below if you need me to elaborate on my response. :)