General Chemistry Answers

how many grams of lactose must be added to 655 grams of water in order to prepare a solution with a percent mass concentration of 10%?

1.What is the vapor pressure of the pure solvent if the vapor pressure of a solution of 15g sucrose (C12H22O11) in 100g of ethanol (C2H5OH) is 58 mmHg?

2.A solution prepared by adding 10g of an unknown non-volatile, non-electrolyte solute to 150 g of water. The Boiling point of the solution is elevated by 0.433 0C above the normal boiling point of the solvent. What is the molar mass of the unknown substance?

3.You add 1 kg of ethylene glycol (C2H6O2) antifreeze to 4500g of H2O in your car’s radiator. What would be the freezing point of the solution?

4.How many grams of Lactic acid (C6H10O5) should be dissolved in 650g of cyclohexane (C6H12) to raise the boiling point to 84.910C? The normal boiling point of cyclohexane is 810C and its molal boiling point is 2.75 0C/m.

5.The osmotic pressure of 250mL of an aqueous solution containing 0.150g of the enzyme lysozyme is found to be 0.0013atm at 24.850 Calculate the molar mass of lysozyme.

Hydrogen peroxide (H2O2) is a powerful oxidizing agent used in concentrated solution in rocket fuels and in diluted solutions is hair bleach. An Aqueous solution of 25% (m/m) has a density of 1.05 g/ml. Calculate the concentration in terms of:

a. Mole Fraction of H2O2

b. Molarity

An ethanol solution is prepared by dissolving 15 mL of ethanol (C2H5OH) (density: 0.850 g/ml) in a sufficient volume of water to produce 120 mL of solution with a density of 0.980 g/mL. What is the concentration of ethanol in this solution expressed as:

a. Volume percent

b. Mass percent

c. Mass/volume percent

d. Mole fraction of Ethanol

e. Molarity

f. Molality

1.How many mL of 0.250 M barium nitrate are required to precipitate as barium sulfate all the sulfate ions from 50 mL of 0.350 M aluminum sulfate?

3 Ba(NO₃)_{2 (aq)}           +       Al₂(SO₄)_3 (aq)     -->   3 BaSO_{4 (s)}  + 2 Al(NO₃)_{3 (aq)}

1. 2.5 mL of nitric acid, HNO₃, are required to react with 50 mL of a 1.25 M Barium hydroxide, Ba(OH)₂ solution:

2 HNO_3 (aq)           +      Ba(OH)_{2 (aq)} -->    2 H₂O _(aq)    +      Ba(NO₃)_{2 (aq)}

Determine the concentration (Molarity) of the nitric acid solution (HNO₃).

Black iron oxide is an ore containing iron and oxygen that occurs in magnetite. A 2.4480 g sample of the ore is found to contain 1.7714g of iron. Calculate the empirical formula of black iron oxide.​

Determine the solubility of the following ionic compounds when added to water by inserting (aq) (s) in formula. Explain how you arrived at your anwer

Sr(HO)2

True or False.

1. Polyhaloalkanes are compounds obtained by replacing two or more H atoms in a hydrocarbon with halogen atoms.

2. A functional group is an atom or a group of atoms the presence of which confers characteristic properties to the compound.

3. Polymers are very large molecules made of repeating structural units called monomers.

4. The group of lipids are subclassified based on whether they can udergo saponification or not.

5. Biomolecules are non-carbon-containing compounds which are of biological importance as they make up and carry out by their chemical reactions the needs of the living organism where they are.

6. Carbohydrates possessing sweet taste are called glucose.

7. Carbohydrates are a group of various oily or waxy substances with long-chain hydrocarbon groups present in or derived from living organisms.

True or False.

1. Carbon atoms have the unique ability to form weak bonds with each other in different ways.

2. Carbon forms four covalent bonds, using hybrid atomic orbitals in bond formation.

3. Hybridization involves the mixing and arrangement of pure atomic orbitals resulting in combinations of s, p, and d orbitals, which are identical in stability and reactivity.

4. Alkenes are open-chain hydrocarbons with single covalent bonds between the carbon atoms.

5. Alkanes are open-chain hydrocarbons with at least one double bond between carbon atoms.

6. Hydrocarbons contain only hydrogen and carbon atoms and are the simplest organic compounds.

7. Condensed ring systems are those that consist of two or more benzene rings joined together in chains or rings.

8. Hydrocarbon derivatives are compounds obtained when other elements are added or substituted to the hydrocarbon components during physical reaction.

Calculate the pH of black coffee with a hydrogen ion concentration of 4.55 × 10⁻⁶ mol dm⁻³. Show all steps of your calculations and include the correct units where needed. Give your pH value to three significant figures. Is coffee an acidic or basic solution? Explain your choice.