<span>How many moles of sodium chloride (NaCl) solute are in 155 grams of an 85.5 percent by mass solution?
1) Calculate the mass of solute
% = [mass of solute / mass of solution] * 100 =>
mass of solute = [% / 100] * mass of solution = [85.5/100] * 155 g = 132.525 g
2) Pass to moles using the molar mass, MM, of NaCl
MM = 23 g/mol + 35.5 g/mol = 58.5 g/mol
n = mass (g) / MM = 132.525 / 58.5 = 2.27 mol
Answer: the second option of the list
4. How many grams of zinc metal will react completely with 8.2 liters of
3.5 M HCl? Show all of the work needed to solve this problem.
Zn (s) + 2 HCl (aq) ---> ZnCl2 (aq) + H2 (g)
From the molarity, calculate the number of mols of HCl
M = n/V => n = M*V = 3.5 mol/liter * 8.2 liter = 28.7 mol HCl
From the reaction: [1 mol Zn / 2 mol HCl] * 28.7 mol HCl = 14.35 mol Zn
Pass to mass, using the atomic mass of Zn
mass = n*atomic mass = 14.35 mol * 65.4 g/mol = 938.5 g Zn
Answer: 938.5 g.
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I believe it’s friction transfers kinetic energy to heat
To find out how many grams are in 4.65 moles of Al(NO₂)₃
Find out what the molar mass of Al(NO₂)₃ is
Al = 26.98 g/mol Al
N = 14 g/mol N
O = 16 g/mol O
Next, you have to look at the subscripts and figure out which they belong to, in this case:
Al = 26.98 g/mol Al
N₃ = 42 g/mol N₃
O₆ = 96 g/mol O₆
Finally, add the numbers together, so:
26.98 g/mol Al + 42 g/mol N₃ + 96 g/mol O₆ =
164.98 g/mol Al(NO₂)₃
Now, you have 4.65 mol Al(NO₂)₃ so
164.98 g/mol Al(NO₂)₃ × 4.65 mol Al(NO₂)₃ =
767.157 grams of Al(NO₂)₃
Answer:
By losing an electron
Explanation:
Electrons have a negative charge. So, losing one would give an element a more positive charge. You can usually find a hydrogen ion (H+) in substances like acids.
