Work out an empirical formula from percentage composition by mass or from combustion data, convert a formula back to percentage composition, and deduce the molecular formula from the empirical formula and the molar mass.
Tę umiejętność sprawdza 29 zadań wzorowanych na arkuszach IB z lat 2022–2026.
Sulfapyridine is an antibacterial drug. Its structure is shown below. C11H11N3O2S Mr = 249.32 (i) Deduce the hybridization of the nitrogen atom that is part of a ring. (ii) Describe how the sigma (σ) and pi (π) components of an…
What is the empirical formula of an alcohol with 60.0 % mass carbon and 13.4 % mass hydrogen? A. C3H7 B. C6H16O2 C. C3H8O D. C2H6O
(i) Determine the molecular formula and the empirical formula of cresolphthalein. (ii) A simplified infrared (IR) spectrum of cresolphthalein is shown below. State the bonds responsible for the absorptions labelled P, Q and R. Use section 20 of the data…
Which of the following could be the empirical formula of a compound with Mr = 70? I. CH2 II. C4H6O III. C5H10 A. I and II only B. I and III only C. II and III only D. I, II and III
(i) Suggest a reason for the slight change in colour observed after the night in the oven. (ii) Suggest how the students could make sure that dehydration in the crucible was complete. (iii) Suggest one way in which the students could reduce the effect of…
Each student used a different mass of the hydrated salt. The results of the whole class are shown below (Mr of H2O = 18.02). (i) Determine the two missing values in the table. The class results were plotted on the graph below. (ii) Draw a line of…
Calculate the percentage by mass of hydrogen in compound Y, giving your answer to four significant figures. Use section 7 of the data booklet.
What is the empirical formula of a compound with the following composition by mass? A. C6HO4 B. C4H8O C. C2H4O D. C4H8O2
When 3.71 g of Z was burned completely in excess oxygen, 8.81 g of carbon dioxide and 4.51 g of water were collected. Determine the empirical formula of Z. Use sections 1 and 7 of the data booklet.
4.81 g of sulfur was heated in a stream of chlorine gas until the reaction was complete. The mass of the chloride produced was 10.13 g. (i) Calculate how many atoms are present in this 4.81 g sample of sulfur. Use sections 2 and 7 of the data booklet. (ii)…
Determine the empirical formula of HA from the percentage composition.
State the molecular formula of HA, using your answers to (a) and (b).
10.0 cm3 of a gaseous hydrocarbon, CxHy, is burned completely in exactly the required volume of oxygen. The gaseous products occupy 70.0 cm3. This falls to 30.0 cm3 once the water vapour present condenses, with…
Outline why compound A cannot be a hydrocarbon.
Determine the empirical formula of A.
At 150.0 °C and a pressure of 1.00 × 105 Pa, the vapour of A has a density of 2.45 × 103 g m−3. Determine the molar mass of A and hence its molecular formula. Use sections 1 and 2 of the data booklet.
What is the molecular formula of the compound with empirical formula CH2 and the following mass spectrum? A. C4H8 B. C6H12 C. C7H14 D. C8H16
Demonstrate that these data are consistent with the formula MgSO4 ⋅ 7 H2O.
Deduce what the graph shows about the water in hydrated magnesium sulfate.
Which compound has the highest percentage of carbon by mass? A. CH3CH2OH B. CH3CHO C. C3H8 D. C2H6
(i) State which two further mass measurements are needed to find the oxide composition. (ii) Outline how these measurements give the mass of oxygen removed from the sample.
3-Methylbutanoic acid reacts with propan-1-ol, CH3CH2CH2OH, to form an organic product and water. Deduce the structural formula and the empirical formula of the organic product.
Hydrogen peroxide has the molecular formula H2O2. Which statement about this formula is correct? A. It shows that the two oxygen atoms are joined by a double bond B. It is the same as the empirical formula of hydrogen peroxide C. It shows that one mole…
An unknown organic compound, X, contains only carbon, hydrogen and oxygen. Elemental analysis shows that it contains 54.5 % carbon and 36.3 % oxygen by mass. (i) Determine the empirical formula of X. The mass spectrum of X is shown. (ii) Identify the species…
Magnesium ribbon of known mass was heated strongly in a crucible, and the heating was repeated until the mass no longer changed. The final mass of the solid was then recorded. Assume that magnesium oxide is the only product. Which of the following can be…
(i) Draw one Lewis (electron dot) structure of the sulfate ion. (ii) Calculate the percentage of oxygen present in the double salt. (iii) Determine the empirical formula of the double salt. Use section 7 of the data booklet. (iv) The molar mass of the…
Calculate the percentage by mass of carbon in ethanoic acid.
A compound contains only carbon, hydrogen and oxygen. Complete combustion of 4.60 g of the compound produces 8.80 g of carbon dioxide and 5.40 g of water as the only products. Which is the empirical formula of the compound?…
A 7.60 g sample of an oxide of nitrogen contains 4.80 g of oxygen. What is the empirical formula of the oxide? A. N2O B. NO2 C. N2O3 D. N2O5
Zapisujemy na Twoim urządzeniu to, bez czego serwis nie działa, np. zalogowanie. Plików analitycznych użyjemy tylko za Twoją zgodą. Szczegóły w polityce prywatności.