please help thank you In order to receive full credit you must Shown below is a

Question

please help thank you

In order to receive full credit you must Shown below is a chemical reaction for which the reactants and products are unknown A + B rightarrow C + D Forty million trillion (40 times 10^12) formula units of A have a mass of 4.26 mg. Substance A is a gray solid that consists only of an alkaline earth metal and carbon (37, 5% carbon mass). There is only one metal atom per formula unit of A. This info can be carbon in one male of the used in conjunction with the molar mass of A to find the # mole of compound-ie. the subscript far carbon in the chemical formula. You should also be able to determine the identity of the metal After these 2 dues you should have the chemical formula for substance A.

Explanation / Answer

Forty million trillion (4x10^19) formula units of A have a mass of 4.26 milligrams.
*47.9 grams of substance B contains 5.36 grams of hydrogen and 42.5 grams of oxygen.

40 million trillion ==40×10^6×10^12=4.000×10^19

where we have used 4 S.F.

4.000×10^19 moleculces of A×1 mol A /6.022×10^23=6.642×10^5mol A

Molar mass of A=4.26×10^3g A / 6.642×10^5mol A=64.1 g/mol

The mass of carbon in one mole of A is

=64.1 g A×37.5 g C /100.0 g A=24.0 g carbon=2 mo lcarbon in substance A

The remainder of the molar mass (64.1 g – 24.0 g = 40.1 g) is due to the alkaline earth metal.From the periodic table, calcium has a molar mass of 40.08 g/mol; therefore,

th e formula of substance A is CaC       -answer

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MW A = .00426 g / [4 x 10^19 / 6.02 x 10^23] = 64, which is 40 + 2*12 for CaCarbon2,

B is H2O, from mass ratio and AtWts H&O

Since C burns giving H2O and CO2, C contains Carbon and Hydrogen.

10 g C gives 33.8 g CO2. CO2 is 12/44 Carbon, so 33.8 g CO2 contains 33.8*12/44g =9.21 g Carbon. 1 g C contains .921 g Carbon.

6.92 g H2O contains 6.92*2/18 = .769g Hydrogen, 1g C contains .0769 g Hydrogen.

.921 gCarbon /12 g/mol = .07675 mol carbon

.0769 g H/ 1 g/mol = .0769 Hydrogen
.07675/.0769 = 1.00 [rounding and at wt errors showing up here, carbon not 12 but 12.011, O 15.994, etc]
So substance has equal numbers of Hydrogen and Carbon atoms, ie, formula is CH, or C2H2, or C3H3, etc.
MW C = 26 means formula is C2H2, acetylene.

So A + B => C + D is CaC2 + H2O => C2H2 + CaO

So 45g A = 45/64 = .703 mol, so you will get .703 mol C2H2, ie .703*12 = 18.3 g acetylene.

47.9 grams B contains 5 .4 grams of H and 42.5 grams of O

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