Chapter 13 - water TEST

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1. Calculate the energy needed to heat 80.0ml of water from 17.0°C to 50.0°C. Specific heat capacity of water = 4.18J/g/C (assume density of water is 1.0 g/mL)
A) 11 kJ B) 12.43 J C) 14 kJ D) 16.1 J E) 0.12 kJ

2. 20.00 mL of pure water at 20.40 oC was heated to 23.40 oC. What amount of energy, in Joules, was used if the specific heat capacity of water is 4.18J/g/C and the density of water is 1.00 g/mL?
A) 0.25 J B) 2.5 J C) 2,500 J D) 2.50 kJ E) 250 J

3. A 40 gram sample of substance "Y" is added to 100 grams of water at 20 oC. How much more of substance "Y" needs to be added to make a saturated solution?
A) The mass that needs to be added is closer to 60 grams. B) The mass that needs to be added is closer to 12 grams. C) The mass that needs to be added is closer to 52 grams. D) The mass that needs to be added is closer to 40 grams. E) The mass that needs to be added is closer to 32 grams.

4. A salt crystal was placed in a salt solution as shown on the right. Which one of the following terms best describes the solution before the crystal was added?
A) Unsaturated B) Saturated C) Supersaturated D) Polysaturated E) Heavy

5. Salt was added to water to form a saturated solution at 0 oC. More salt was later added and the solution heated to 60 oC. The solution was then slowly cooled to 0 oC without crystallisation. Which term best describes the solution at 0 oC?
A) Dilute. B) Polyunsaturated C) Saturated. D) Unsaturated. E) Supersaturated.

6. Convert 0.0025%(m/v) to mg/L
A) 2.5 mg/L B) 250 mg/L C) 25 mg/L D) 0.25 mg/L E) 0.025 mg/L

7. Baby Jon has a high temperature and his mother wants to give him paracetamol to treat the fever. The doctor instructs Jon's mother to give him 15.0 mg per 1 kg of body mass. The bottle of paracetamol syrup has the concentration 24.0 mg per mL on the label. If Jon's mass is 10.0 kg what volume of syrup should Jon be given?
A) 6.25 mL B) 16.5 mL C) 24.0 mL D) 36.0 mL E) 12.4 mL

8. 30 mL of a plant food solution contains 1.5g of ammonium nitrate. What is the percentage concentration (w/v) of ammonium nitrate?
A) 0.2% B) 2% C) 9% D) 3% E) 5%

9. 300 mL of a plant food solution contains 2.5g of phosphate. What is the percentage concentration (w/v) of phosphate?
A) 4.5% B) 0.83% C) 0.45% D) 0.76% E) 0.89%

10. 40g of salt solution contains 8 g of slat. What is the percentage concentration (w/w) of this solution?
A) 40% B) 30% C) 25% D) 15% E) 20%

11. The solubility of oxygen gas at 20 oC is 0.043grams per kilogram of water. Calculate the percentage concentration(w/w)
A) 1.3 X 10-3%(w/w) B) 4.3 X 10-3%(w/w) C) 4.3 X 10-2%(w/w) D) 3.3 X 10-3%(w/w) E) 3.3 X 10-4%(w/w)

12. What mass of water must be used to dissolve 10g of salt in order produce a salt solution of 12%(w/w)?
A) 44 g B) 12 g C) 23 g D) 34 g E) 73 g

13. Look at the image on the right. Which ONE statement is TRUE?
A) The water represents the solute which is dissolved by the solvent(sugar) B) The solute always dissolves the solvent. C) The more solute present the more DILUTE the solution becomes. D) The sugar represents the solute which is dissolved by the solvent(water) E) None of the comments above are correct.

14. What is the temperature at which 92 grams of substance A can dissolve in 100 grams of water?
A) 8 oC B) 18 oC C) 48 oC D) 50 oC E) 38 oC