If hydrochloric acid (HCl) reacts with sodium hydroxide (NaOH), which ions from each reactant participate in forming water?
H+(aq) from HCl and OH-(aq) from NaOH
Neutralisation between a strong acid and a strong base is essentially the combination of the acid's hydrogen ion with the base's hydroxide ion to form water.
Hydrochloric acid dissociates in water as HCl → H+(aq) + Cl-(aq), so the H+ comes from HCl.
Sodium hydroxide dissociates as NaOH → Na+(aq) + OH-(aq), so the OH- comes from NaOH.
The net ionic reaction is H+(aq) + OH-(aq) → H2O(l); Na+ and Cl- stay in solution as spectator ions and later form NaCl on evaporation.
Hence, water is formed from H+(aq) of HCl and OH-(aq) of NaOH.
Which of the following mixtures is NOT homogeneous?
Who was the first scientist to use the term 'element'?
Match the compound to its respective mass ratio by elements from the table given below.
| Compound | Mass Ratio by Elements |
| 1. Water (H2O) | A. 1 : 8 |
| 2. Carbon dioxide (CO2) | B. 14 : 3 |
| 3. Ammonia (NH3) | C. 3 : 8 |
| 4. Sulphur dioxide (SO2) | D. 1 : 1 |
Which of the following most accurately represents a heterogeneous mixture?
Among the following, what has a molecular mass of 44 u?
When 16 g of oxygen is combined with 2 g of hydrogen, 18 g water is formed. This observation is in accordance with:
Methyl orange turns red in:
Why is the reaction flask corked during experiments verifying conservation of mass?
Which of the following is a heterogenous mixture?
Given that the atomic masses of C = 12 u, O = 16 u and H = 1 u, which of the following options correctly represents the molecular masses of CO2 and H2O?