General Chemistry Answers

The molal boiling point constant of water is 0.512ºC/m. If 1 mol cane sugar (342g/mol) is dissolved in 1kg water, the solution will boil at 100.512ºC, assuming standard pressure. By this relationship, half of a mole of sugar (171g) would boil at 100.256 C/m and 2 mol sugar (684g) should boil at 101.024ºC/m. However, these are not necessarily solutions that can be mixed; 684g of sugar is nearly a pound and a half of sugar, which you are supposed to dissolve in a liter of water!

From the given situation above, why is it important to understand the constants relating to water?

The molal freezing point of water is 1.86ºC/m (1.86K/m), which can be expressed as 1.86ºC ● kg H2O/mol solute (1.86K ● kg H2O/mol solute) after some algebraic rearrangement. This means that a solution of 1 mol cane sugar (342g, over 3 4 lb) dissolved in 1kg of water should freeze at -1.86ºC.

Describe the freezing point drop suggests in number 1.

Give two examples of alloys alongwith their compositions and uses.

Calculate the mass (g) of magnesium oxide produced when 500 g of magnesium reacts with oxygen in the air.

2Mg + O2 → 2MgO

Calculate the pH of an acetic acid solution at 3.20 x 10-4 mol/L (% ionization = 1.30%).

Determine the [H3O+(aq)] of a solution with a pH of 3.45.

Expressed in scientific notation, the answer is in the form a,b × 10–c.

red giant star becomes exhausted of nuclear fuel, the outer material is blown off into space leaving the inert Carbon. The remnant is known as WHITE DWARF.

the star is unable to generate heat when it runs out of hydrogen in its core leading to its contraction and expansion. It cools down and glows red. The helium fused into Carbon. The star is now a RED GIANT.

Given the balanced equation:  CH₄ + 2 O₂ → CO₂ + 2H₂O 

If 3.6 moles of CH₄ react in the above reaction, how many moles of oxygen gas, O₂ reacted?

Calcium sulfate is known to form hydrates (ionic compounds with water that have well-defined ratios of the ionic formula unit to molecules of water, written CaSO4⋅nH2O). The water content of the hydrate can be determined by gravimetric analysis. How many molecules of water are present for every formula unit of CaSO4 in an unknown calcium sulfate hydrate if a complete drying of a sample to anhydrous caused its mass to decrease from 8.609g to 6.807g?

• Use 136.14g/mol for the formula mass of CaSO4
• Use 18.02g/mol for the formula mass of H2O