These are called ocean or underwater trenches <span />
Answer:
b) add 130 g of NaCH₃CO₂ to 100 mL of H₂O at 80 °C while stirring until all the solid dissolves, then let the solution cool to room temperature.
Explanation:
The solubility of NaCH₃CO₂ in water is ~1.23 g/mL. This means that at room temperature, we can dissolve 1.23 g of solute in 1 mL of water (solvent).
<em>What would be the best method for preparing a supersaturated NaCH₃CO₂ solution?</em>
<em>a) add 130 g of NaCH₃CO₂ to 100 mL of H₂O at room temperature while stirring until all the solid dissolves.</em> NO. At room temperature, in 100 mL of H₂O can only be dissolved 123 g of solute. If we add 130 g of solute, 123 g will dissolve and the rest (7 g) will precipitate. The resulting solution will be saturated.
<em>b) add 130 g of NaCH₃CO₂ to 100 mL of H₂O at 80 °C while stirring until all the solid dissolves, then let the solution cool to room temperature. </em>YES. The solubility of NaCH₃CO₂ at 80 °C is ~1.50g/mL. If we add 130 g of solute at 80 °C and let it slowly cool (and without any perturbation), the resulting solution at room temperature will be supersaturated.
<em>c) add 1.23 g of NaCH₃CO₂ to 200 mL of H₂O at 80 °C while stirring until all the solid dissolves, then let the solution cool to room temperature.</em> NO. If we add 1.23 g of solute to 200 mL of water, the resulting solution will have a concentration of 1.23 g/200 mL = 0.00615 g/mL, which represents an unsaturated solution.
We will assume that the solvent is water. So, if we have 100 grams of the solution, 19 grams will be sodium hydroxide, while the remaining 81 grams will be water.
The molar weight of sodium hydroxide, NaOH, is 40. The molar weight of water is 18. Finding the moles of each:
NaOH:
19 / 40 = 0.475
Water:
81 / 18 = 4.5
Total moles present:
4.5 + 0.475 = 4.975 moles
The mole fraction of NaOH is:
0.475 / 4.975 = 0.0955
The mole fraction of NaOH is 0.0955
Answer:
The correct option is;
B. Increase by $4 billion
Explanation:
In Gross Domestic Product, (GDP) calculation based on the spending or expenditure approach, the spending components of the countries different economic groups are calculated
The formula for the GDP can be expressed as follows;
GDP = C + G + I + NX
Where;
C = Consumer spending or private sector consumption
G = Spending by the government
I = Economic investment
NX = Net export of goods by the economy.
