Finding unknown substances and masses

[00_Furon]

From the information below, determine the mass of substance C that is formed if 45.0 g of substance A reacts with 23.0 g of substance B, assuming that the reaction between A and B goes to completion.
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a. Substance A is a gray solid that consists of an alkaline Earth element and carbon; the m% carbon in the compound is 37.5%. It reacts with substance B to form substances C and D. 4.0 x 1016 formula units of compound A weighs 4.26 micrograms.

b. 47.9 g of substance B contains 5.36 g H and 42.5 g O.

c. When 10.0 g of substance C is burned in excess oxygen, 33.8 g of CO2 and 6.92 g of H2O are produced. The molar mass of substance C is MC = ~26 g/mol.

d. Substance D is the hydroxide of the metal in substance A.

 

[nate808]

To determine the mass of substance C formed in the reaction, we need to use the given information to calculate the number of moles of substance A and B, and then determine the limiting reagent. The limiting reagent is the substance that will be completely consumed in the reaction, and therefore determines the amount of product formed.

a. To calculate the number of moles of substance A, we first need to convert the given mass of 4.0 x 1016 formula units to moles. We can do this by using the molar mass of substance A, which can be calculated using the given information about its composition. Substance A consists of 37.5% carbon, which means that the remaining 62.5% must be the alkaline Earth element. This gives us a molar mass of (0.375 x 12.01 g/mol) + (0.625 x atomic mass of alkaline Earth element g/mol).

Now, we can use the given information that 4.0 x 1016 formula units of substance A weighs 4.26 micrograms to calculate the molar mass of substance A. This gives us a molar mass of 4.26 micrograms / (4.0 x 1016) = 1.065 x 10^-20 g/mol. Converting this to grams/mol gives us a molar mass of 1.065 x 10^-23 g/mol.

Next, we can use the given mass of 45.0 g of substance A to calculate the number of moles of substance A:

45.0 g / (1.065 x 10^-23 g/mol) = 4.22 x 10^23 mol of substance A.

Similarly, we can calculate the number of moles of substance B using its given mass of 23.0 g and its molar mass of 47.9 g/mol:

23.0 g / 47.9 g/mol = 0.481 mol of substance B.

b. From the given information, we can determine that 47.9 g of substance B contains 5.36 g of hydrogen and 42.5 g of oxygen. Using the molar masses of hydrogen (1.008 g/mol) and oxygen (16.00 g/mol), we can calculate the number of moles of each element present in 47.9 g of substance B:

5.36 g H / 1