Hello please help me I need help today with my chemistry homework and i am on the verge of tears please help me.

Question

1.) S   + 6 HNO3 --> H2SO4 + 6 NO2 + 2 H2O

In the above equation how many moles of water can be made when 163.6 grams of HNO3 are consumed?

Round your answer to the nearest tenth. If you answer is a whole number like 4, report the answer as 4.0

Use the following molar masses. If you do not use these masses, the computer will mark your answer incorrect.:

Element	Molar Mass
Hydrogen	1
Nitrogen	14
Sulfur	32
Oxygen	16

2.) 3 Cu + 8HNO3 --> 3 Cu(NO3)2   + 2 NO + 4 H2O

In the above equation how many moles of water can be made when 118.6 grams of HNO3 are consumed?

Round your answer to the nearest tenth. If you answer is a whole number like 4, report the answer as 4.0

Use the following molar masses. If you do not use these masses, the computer will mark your answer incorrect.:

Element	Molar Mass
Hydrogen	1
Nitrogen	14
Copper	63.5
Oxygen	16

please helps please

Answer 1

Hi, Mandy I will try to teach you how to do these problems.

Consider the hypothetical reaction 2 A ====== > 3 B where A and B are hypothetic substances. A has a molecular mass of 25 and B 40.

Case 1: you are given the number of moles of A and asked to determine the number of moles of B produced.

Set up the conversion factor 3 moles B / 2 moles A which you get from the balanced equation. Note that the thing you want to find is in the numerator. Now multiply the factor by the number of moles of A you were given, let's say it's 5 moles of A. The calculation is 3 moles B / 2 moles A x 5 moles A = 7.5 moles of B produced. Note that moles of A units cancel leaving only moles B.

Case 2: you are given the # grams of A and asked to calculate the number of moles of B produced.

Set up this conversion factor 3 moles B / 2 x molecular mass of A (25). This becomes 3 moles B / 2 x 25 g A

or 3 moles of B / 50 g A. Again notice that the thing you are trying to calculate is in the numerator. Now multiply the conversion factor by the number of grams of A you are given, let's say 35 g.

The calculation is 3 moles B / 50 g A x 35 g A = 2.1 moles B produced.

Case3: you are given the number of grams of A and asked to find the number of grams of B produced.

The conversion factor here is 3 x molecular mass of B ( 3 x 40g) / 2 x molecular mass of A (2 x25g) or

3x 40g / 2 x 25 g = 2.4 g B / g A. Now multiply by the number of grams of A given ( let's say 5.0 g A) to get

2.4 g B / g A x 5.0 g A = 12.0 g B produced.

There are variations to these cases, but the general procedure is to write a conversion factor for what you are trying to find, putting the thing you are trying to find in the numerator, then multiply by the given quantity.

Now let's do the first problem. The problem asks for the moles of H2O produced from 163.6 g HNO3. The conversion factor is 2 moles H2O / 6 x mol. mass of HNO3 or 2 moles H2O / 6 x 63 g/mol but you are given 163.6 g HNO3, so the calculation becomes 2 mol H2O / 378 g HNO3 x 163.6 g HNO3 = 0.9 moles H2O produced.

This is probably not how this is presented in school, but I find it less confusing once you understand the procedure. Try the second problem yourself. The answer should be 0.9 moles H2O

Answer 2

#1)

Step 1: Determine the molar mass of HNO₃ (aka mass of one mole of HNO₃ molecules)

In one HNO₃ molecule, there is... 1 H atom, 1 N atom, and 3 O atoms.

Molar Mass = 1(1) + 1(14) + 3(16) = 63 g/mol

Step 2: Determine the moles of HNO₃ reacted

Each mole of HNO3 is 63 g.

163.6 g x 1 mol/63 g = 2.6 mol

Step 3: Determine the moles of water produced (with the available HNO₃)

Based on the balanced chemical equation, for every 6 moles HNO3 reacted, 2 moles of H2O are produced.

2.6 mol HNO3 x (2 mol H2O / 6 mol HNO3) = 0.9 mole H2O

#2)

Even though the chemical formula is different, the same idea can be applied here...

Step 1:

Molar Mass = 63 g/mol

Step 2:

118.6 g x 1 mol/63 g = 1.88 mol

Step 3:

Based on the balanced chemical equation, for every 8 moles HNO3 reacted, 4 moles of H2O are produced.

1.88 mol HNO3 x (4 mol H2O / 8 mol HNO3) = 0.9 mole H2O

P.S. You got this! :-)