PLEASE DO THE EXERCISE #1, #2, #3, #4. DO ALL THE STEPS AVAILABLE IF YOU GIVE ME

Question

PLEASE DO THE EXERCISE #1, #2, #3, #4. DO ALL THE STEPS AVAILABLE IF YOU GIVE ME THE RIGHT ANSWER I WILL LIKE AND GIVE GOOD FEEDBACK TO CHEGG ass is Name Nigel HW: Chapter 11 Due February 1,2017 1. What ions are present after the following salts are dissolved in water Cyou may need to review monatomicand polyatomic ions from Gen Chem 1): Na SO Na2S04 NH4Br MgF2 2. A solution was prepared by dissolving 25.0 mL pentane (osH12, d 0.63 g/mL) in 45 mL of hexane (C6H1 d 0.66 g/mL). Calculate the concentration in: Molarity (M) M moles so e Molality (m) en Mass percent vnass s vnoss solute IS MS u 63 g total mass. 3. a. Which solvent would you use to dissolve co2: water or carbon tetrachloride? Which solvent would you use to dissolve CH30H: water of hexane (CoH) What is the freezing point of an aqueous solution that has 25.0 g of C12H22011 per 100 g of H20? The normal freezing point of H20 is 0 C and Kf 1.86 C/m

Explanation / Answer

ANSWER 1:

Na2SO4 :

Cations: 2 sodium ions that is, Na+

Anions: sulphate ions which are SO42- .

NH4Br :

Cations: NH4+ that is ammonium ions

Anions: Br- that is bromine ions

MgF2 :

Cations: Mg+2

Anions: 2 fluoride that is F- ions

ANSWER 2:

volume of pentane = 25 mL

density of pentane = 0.63 g/mL

therefore mass of pentane = 0.63*25 = 15.75 g

Molecular weight of pentane (M.W)= 72.15 g/mol

moles of pentane = mass/MW = 15.75/72.15 = 0.2183 mol

similarly, mass of hexane = 0.66*45 = 29.7 g

molecular weight is hexane (M.W) = 86.18 g/mol

moles of hexane = 29.7/86.18 = 0.3446 mol

Molarity (M) = moles of solute(pentane)/ volume of solution in L

M = 0.2183/(45*10-3 ) = 4.851 M

Molality = moles of solute (pentane)/ kg solvent

m = 0.2183/(29.9*10-3 ) = 7.301 m

mass percent = mass of solute/total mass = 15.75/(15.75+29.7) = 0.3465

ANSWER 3:

part (a)

Organic compounds are more soluble in organic solvents and less in inorganic solvents. Water is an inorganic solvent while carbon tetrachloride is an organic one. Hence, it should be dissolved in carbon tetrachloride.

part (b)

With same above explanation in part (a), methanol (CH3OH) should be dissolved in hexane.

ANSWER 4:

first calculate the molality of solution

molecular weight of C12H22O11 = (12*12)+(1*22)+(11*16) = 342 g/mol

moles of solute = 25/342 = 0.07309

m = moles of solute/(kg solvent) = 0.07309/(100*10-3 ) = 0.7309 m

(freezing point of pure solvent) - (freezing point of solution) = Kf * molality

0- (freezing point of solution) = 1.86*0.7309

(freezing point of solution) = -1.359 C

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