2. How many grams of sucrose (C 12 H 22 O 11 ) are in 2.0 L of 0. 650M sucrose s

Question

2.         How many grams of sucrose (C12H22O11) are in 2.0 L of 0. 650M sucrose solution?

3.         What volume of 0.150 M HNO3 solution will completely react with 25.0 mL of 0.105 M Na2CO3 solution according to the following balanced equation (write the products and balance it first)?

            Na2CO3 (aq) + HNO3 (aq) --->

4.         Pollution is a growing problem. Bodies of water are continually being polluted, which in turn harms the creatures living in the water. How might you find the amount of acid in a lake? Why would it be important to know the amount of acid in the lake?

Explanation / Answer

2. Molarity of C12H22O11 = number of moles of sucrose/volume of solution in litres

0.650 = number of moles of sucrose/2

So number of moles of sucrose = 2 x 0.650 = 1.3

number of moles of sucrose = weight of sucrose/molecular weight of sucrose

1.3 = weight of sucrose/342

So weight of sucrose = 1.3 x 342 = 444.6 g

3.    The balanced equation can be written as

Na2CO3 (s) + 2HNO3(aq) 2NaNO3(aq) + CO2(g) + H2O(l)

CO2 dissolves into water and form carbonic acid that is H2CO3.

2* M(HNO3) V(HNO3) = M(Na2CO3) V(Na2CO3)

   2 * 0.150 * V(HNO3) = 0.105 * 25

V(HNO3) = 0.105 * 25 / ( 2 * 0.150 ) = 8.75 mL

4. If the pH of water is too high or too low, the aquatic organisms living within it will die because of higher BO. pH can also affect the solubility and toxicity of chemicals and heavy metals in the water. The majority of aquatic creatures prefer a pH range of 6.5-9.0.

Aquatic species are not the only ones affected by pH. While humans have a higher tolerance for pH levels (drinkable levels range from 4-11 with minimal gastrointestinal irritation). pH values greater than 11 can cause skin and eye irritations, as does a pH below 4.

There are many factors that can affect pH in water both natural and man-made. Most natural changes occur due to interactions with surrounding rock (particularly carbonate forms) and other materials. pH can also fluctuate with precipitation (especially acid rain) and wastewater or mining discharges. In addition, CO2 concentrations can influence pH levels.

Therefore it is necessary to to know the exact amount of acid in the lake.

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