<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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Answer:
c) disaccharides have more chemical bonds
Explanation:
disaccharides are made from the condensation of two monosaccharides.
This means there are more bonds in disaccharides. More bonds mean greater energy and vice versa .
Answer: A) polar molecule
Explanation: Polar molecules are molecules which contain atoms of different electronegativities.
Non polar molecules are molecules which contains atoms of same electronegativities.
Water is a polar covalent molecule formed by unequal sharing of electrons. Oxygen being more electronegative tend to keep the electron pair towards itself thus generating a partial negative charge. The hydrogen acquire a partial positive charge thus resulting in a polar molecule.
The bent shape is due to repulsion between lone pairs and bond pairs of electrons.
