Ch.9 solutions homework

  1. #36)  what is the difference between a homogeneous mixture and a heterogeneous one?
    Homogeneous  mixture is uniform throughout because the particles size is small. heterogeneous mixture mixing is non uniform because particle size is larger.
  2. #38)  what characteristic of water allows it to dissolve ionic solids?
    the polarity of water enables it to dissolve many ionic solids
  3. #46)  how is molarity (M) defined?
    number of moles of solute per liter of solution
  4. #48)  how would you prepare 750.0 mL of a 6.0% (v/v) ethyl alcohol solution?
    • 6.0mL ethyl alcohol   X 750.0 mL solution
    • 100.0 mL solution

    =45.0 mL ethyl alcohol
  5. #50) describe how you would prepare 250 mL of a 0.10 M NaCl solution.
    250mL solution X 0.10mol NaCl/1000mL solution X 58.5g NaCl / 1mol NaCl 

    =1.5g NaCl
  6. #54) how many moles of each substance are needed to prepare the following solutions? 

    a) 50.0 mL of 8.0% (m/v) KCl (MW= 74.55g/mol)

    b) 200.0mL of 7.5% (m/v) acetic acid (MW=60.05 g/mol)
    a) 0.054 mol KCl 

    b) 15 g acetic acid 

    0.25 mol acetic acid
  7. #58) the lethal dosage of potassium cyanide (KCN) in rats is 10mg KCN per kg of the body weight. what is this concentration is parts per million?
    10mg KCN/ 1kg body weight X 1kg/ 106mg X 106 

  8. #60) what is the molarity of the following solutions? 

    a) 12.5g NaHCO3 in 350.0mL solution
    b) 45.0g H2SO4 in 300.0mL solution
    c) 30.0g NaCl dissolved to make 500.0mL solution
    • a) 0.425 M 
    • b) 1.53 M 
    • c) 1.03 M
  9. #62) how many mL's of a 0.75 M HCl solution do you need to obtain 0.0040 mol of HCl?
    5.3mL HCl
  10. #64) 450mL of 0.50 M H2SO4 spilled. How many grams of NaHCO3 you need to neutralize the acid according to this equation? 
    H2SO4 (aq) + 2 NaHCO3 (aq) --> Na2SO4(aq)+ 2H2O(l)+ 2CO2(g) 
    0.23 mol H2SO4
  11. #70) Concentrated (12.0 M) hydrochloric acid is sold for household and industrial purposes under the name "muriatic acid." how many mL's of 0.500 M HCl solution can be made from 25.0 mL of 12.0 M HCl solution?
    600 mL
  12. #72)  what is an electrolyte?
    a substance that conducts electricity when dissolved in water.
  13. #84) why do red blood cells swell up and burst when placed in pure water? (subject: osmosis)
    the inside of a red blood cell contains dissolved substances and therefore has a higher osmolarity than pure water. water thus passes through the cell membrane to dilute the cell contents until pressure builds up and the cell eventually bursts.
  14. #86) which has the higher osmolarity? 
    a) 0.25 M KBr or 0.20 M Na2SO4

    b) 0.30 M NaOH or 3.0% (m/v) NaOH
    • a) 0.20 M Na2SO4 greater (0.60 osmol)
    • b) 3% (m/v) NaOH greater (1.5 osmol)
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Ch.9 solutions homework