Zadanie 1b
Sulfapyridine is an antibacterial drug. Its structure is shown below. C11H11N3O2S Mr = 249.32 Calculate the mass percentage of nitrogen in sulfapyridine. Use section 7 of the data booklet.
- Materiał graficzny
Empirical and molecular formulas
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 31 zadań wzorowanych na arkuszach IB z lat 2022–2026.
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Zadanie 5
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
Zadanie 1a
Determine the molecular formula and the empirical formula of cresolphthalein.
- Materiał graficzny
Zadanie 2
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
Zadanie 4b
Calculate the percentage by mass of hydrogen in compound Y, giving your answer to four significant figures. Use section 7 of the data booklet.
Zadanie 5a
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.
Zadanie 5
What is the empirical formula of a compound with the following composition by mass? A. C6HO4 B. C4H8O C. C2H4O D. C4H8O2
- Tabela do uzupełnienia
Zadanie 1b
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)…
Zadanie 1a
Determine the empirical formula of HA.
Zadanie 1c
State the molecular formula of HA.
Zadanie 1
Which compound has the highest percentage of carbon by mass? A. CH3CH2OH B. CH3CHO C. C3H8 D. C2H6
Zadanie 1a
Outline why compound A cannot be a hydrocarbon.
Zadanie 1b
Determine the empirical formula of A.
Zadanie 1c
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.
Zadanie 2
A hydrocarbon has the empirical formula CH2 and a molar mass of 98.2 g mol−1. What is its molecular formula? A. C6H12 B. C7H16 C. C7H14 D. C8H16
Zadanie 2a
Demonstrate that these data are consistent with the formula MgSO4 ⋅ 7 H2O.
- Materiał graficzny
Zadanie 2c
Deduce what the graph shows about the water in hydrated magnesium sulfate.
- Materiał graficzny
Zadanie 3
Ethane-1,2-diol has the molecular formula C2H6O2. Which statement about its empirical formula is correct? A. It is CH3O, because it shows the simplest whole-number ratio of the atoms of each element B. It is C2H6O2, because it shows the…
Zadanie 2b
(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.
- Materiał graficzny
Zadanie 1a
Determine the empirical formula of X.
Zadanie 1c
The molar mass of X is 88.1 g mol−1. Determine the molecular formula of X.
Zadanie 2
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…
Zadanie 3
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…
Zadanie 5a
(i) Calculate the percentage of oxygen present in the double salt. (ii) Determine the empirical formula of the double salt. Use section 7 of the data booklet. (iii) The molar mass of the empirical formula is the same as the molar mass of the formula unit.…
Zadanie 1c
Calculate the percentage by mass of carbon in ethanoic acid.
Zadanie 30
Which data can be used to determine the empirical formula of an unknown hydrocarbon? A. The enthalpy change of combustion of the hydrocarbon B. The boiling point and density of the hydrocarbon C. The molar mass of the hydrocarbon D. The masses of carbon…
Zadanie 30
Which data are sufficient to determine the empirical formula of an oxide of a known metal M? A. The density and the colour of the oxide B. The enthalpy change of formation and the melting point of the oxide C. The mass of M used and the mass of oxide formed D.…
Zadanie 2
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?…
Zadanie 3
A compound has the empirical formula CH2Cl and a relative molecular mass of 99. What is the molecular formula of the compound? A. CH2Cl B. C2H4Cl2 C. C3H6Cl3 D. C4H8Cl4
Zadanie 4
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
Zadanie 4
A compound has a relative molecular mass of 58. Which is a possible empirical formula of the compound? A. C2H5 B. CH C. C4H10 D. C3H8