Chemistry Year 12 Random Retrieval

Why is ethanol a liquid while propane is a gas? (Relative atomic masses: C = 12, H = 1, O = 16)

What is the oxidation number of NITROGEN in

NH₄⁺

In which of these molecules do the intermolecular forces arise largely from attractions between temporary dipoles?

Calculate the theoretical yield of ethyl ethanoate, CH₃CO₂C₂H₅, when 6.9 g ethanol, C₂H₅OH, reacts with excess ethanoic acid, CH₃CO₂H.

Sodium hydride reacts with water:

NaH_(s) + H₂O_(l) -> NaOH_(aq) + H_2(g)

What is the concentration of a solution of sodium hydroxide formed when 0.600 g sodium hydride reacts with water and the solution is diluted to 100 cm³?

Typically the molecular compounds of carbon with hydrogen:

(i) are insoluble in water

(ii) form solutions which do not conduct electricity

(iii) are soluble in liquid hydrocarbons

(iv) are denser than water

An ammonia molecule, NH₃, can react to form an ammonium ion, NH₄⁺. When this happens:

(i) the ammonia molecule forms a bond with a proton

(ii) the ion formed has a tetrahedral shape

(iii) a dative covalent bond forms

(iv) the H-N-H bond angle is 90^o

What is the bond angle found in BF₃?

Which of these true statements can help to explain why iodine is a solid while chlorine is a gas at room temperature and pressure?

(i) iodine molecules have a larger surface area than chlorine molecules

(ii) iodine atoms are heavier than chlorine atoms

(iii) the outer shell electrons in iodine atoms are further from the nucleus than they are in chlorine atoms

(iv) the charge on the nucleus of an iodine atom is larger than the charge on the nucleus of a chlorine atom

Which of these compounds dissolve in water and react to form a solution containing hydroxide ions:

(i) sodium oxide

(ii) ammonium chloride

(iii) ammonia

(iv) sodium chloride