Question 7
(a) Cortisol (Molar mass: 362.47 g/mol), one of the major steroid hormones, is a key factor in the synthesis of protein. Its profound effect on the reduction of inflammation explains its use in the treatment of rheumatoid arthritis. Cortisol is composed of 69.6% C, 8.34% H and 22.1% O by mass. What is the molecular formula?
(b) One of the most widespread environmental carcinogens (cancer-causing agents) is benzo[]pyrene (M = 252.30 g/mol). It is found in coal dust, in cigarette smoke, and even in charcoal-grilled meat Analysis of this hydrocarbon shows 95. 2 1 mass % C and 4.79 mass % H. What is the molecular formula of benzo[]pyrene?
(c) Anabolic steroids are sometimes used illegally by athletes to increase muscle strength. A forensic chemist analyses some tablets suspected of being a popular steroid. She determines that the substance in the tablets contains only C, H and O and has a molar mass of 300.42 g/mol. When a 1.200 g sample is studied by combustion analysis, 3.516 g of CO2 and 1.007 g of HO are collected. What is the molecular formula of the substance in the tablets?
Question 8
Nitrogen, N2, and hydrogen, H2, react to form ammonia, NH3. Consider the diagram of N and H shown below.
8
Key
8
Hydrogen
8
8 Nitrogen
8
(a) Write a balanced equation for this reaction; include the phase labels. (b) What is the limiting reagent in this reaction? (c) What is the maximum number of ammonia molecules that can be formed in this chemical reaction? (d) Draw a submicroscopic representation of the contents of the container after the reaction has taken place (use a key as well)
DM (2023)
Question 9
Two oxides of nitrogen have compositions as follows:
Compound 1: 46.68% N and 53.32% O Compound 2: 36.86% N and 63.14% O
Show that these two compounds obey the law of multiple proportions.
Question 10
Balance the following chemical equations (phases or state symbols are not required): (a) Sn+ NaOH NaSnO+H2 (b) Al + Fe3O4 AlO3 Fe (c) PO+ HO HPO4 (d) CHOH CO2 + HO (e) As2S3 + O AsO3 +SO (f) Ca(PO + H;PO4 Ca(HPO
