40) Hydrogen fluoride will react with glass (silicon dioxide, Sio2) according to
ID: 1035273 • Letter: 4
Question
40) Hydrogen fluoride will react with glass (silicon dioxide, Sio2) according to the equation below. What mass of HF is required to react completely with 16.0 g of glass?[Molar masses: Si, 28.09 g/mol; F, 19.00 g/mol; H, 1.01 g/mol; 0, 16.00 g/mol] 4HFe)+ SiO2(s)SiF4(s)+2H20) A) 21.3g B) 80.0g C)5.33 g D)64.0 g E) 320 g 41) Glucose (C6H1206) is an important energy-rich compound, produced by 41) ct photosynthesis according to the equation below. What mass of glucose can be produced from 2.61 mol of CO2 and the necessary water? [Molar masses: C, 12.01 ymol; H. 1.01 g/mol; O, 16.00 g/mol] 6CO2(g)+ 6H200) C6H12060+ 602g) A) 0.0128g B) 0.0869 g C) 414 g D) 78.4 g E) 69.0 g 42) Upon mixing a clear colorless BaCl2 solution with a clear, colorless NagS04 solution42) according to the reaction below, a student observes a white cloudiness form. What is responsible for the cloudiness that is obscrved? BaC2(ag) +Na2SO4(a) BaSO4()+ 2NaC(a) A) Na2SO4 B) NaCI C) BaClh D) BaS04 E) It is impossible to tell without doing the reaction oneself. 43) 43) The fluoride rinse in dental offices usually contains sodium fluoride. Sodium fluoride can be prepared from the reaction between sodium metal and fluorine gas. Which of the following properly represents the balanced chemical equation for this reaction? A) 2Na(s) + F2(e)-? 2Na2F(5) B) 2Na(s) + F2(g) ? 2NaF(s) C) Na(s)+ F(e)- NaF(s) D) Na(s) + F20g_ NaF2(s) E) TNa(s) + FC)--Na7F(5) 44) 44) What is the mass of a 0.150 mole sample of sulfur? E) 214 g A) 4.68 g B) 5.17 g C) 0.208 gD) 4.81gExplanation / Answer
40)
4 HF(g) + SiO2(s) --------------- SiF4g) + 2 H2O(g)
4 moles 1 mole
molar mass of HF = 1.01+19.00 = 20.01 gram/mole
molar mass of glass = SiO2 = 28.00 + 2(16.00) = 60.00 gram/mole
mass of siO2 = 16 grams
according to equation
1 mole of SiO2 = 4 moles of HF
60.00 grams of SiO2 = 4 x 20.01 gra sm of HF
16 grams of SiO2 = ?
= 4x20.01x16/60.00 =21.344 grams
mass of HF required = 21.3 grams
The answer is A.
41)
6 CO2(g) + 6 H2O(l) ------------------ C6H12O6(l) + 6 O2(g)
6 moles 1 moles
molar mass of C6H12O6 = 6(12.01) + 12(1.01) + 6(16.00)=180.18 gram/mole
according to equation
6 moles of CO2 = 1 mole of C6H12O6
6 moles of CO2 = 180.18 grams of glucose
2.61 moles of CO2 = ?
= 180.18x2.61/6 =78.37 grams
mass of glucose formed = 78.4 grams
The answer is D
42)
BaCl2(aq) + Na2SO4(aq) ------------------- BaSO4(s) + 2 NaCl(aq)
The formed BaSO4 precipitate is responsible for the cloudiness.
The answer is D
43)
2 Na(s) + F2(g) --------------- 2 NaF(s)
The answer is B
44)
molar mass of S= 32.0grams/mole
mass of 1 mole of S= 32.07gram
mass of 0.150 moles of S=?
= 32.07x0.150=4.81 grams
The answer is D.
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