A student investigated the production and properties of hydrogen gas.
The student reacted zinc metal with dilute hydrochloric acid to produce hydrogen gas. State two observations that the student could make during this reaction.
Complete the word equation for this reaction:
zinc+hydrochloric acid→+ \text{zinc} + \text{hydrochloric acid} \rightarrow \text{\quad\quad\quad\quad\quad\quad} + \text{\quad\quad\quad\quad\quad\quad} zinc+hydrochloric acid→+Balance the chemical equation for the reaction of hydrogen with chlorine of the form:
‾ H2(g)+‾ Cl2(g)→‾ HCl(g) \underline{\quad\quad} \text{ H}_2(\text{g}) + \underline{\quad\quad} \text{ Cl}_2(\text{g}) \rightarrow \underline{\quad\quad} \text{ HCl}(\text{g}) H2(g)+ Cl2(g)→ HCl(g)To show that a colorless liquid is pure water, the student performed a chemical test and a physical test.
The chemical test involved adding a few drops of the liquid to a sample of anhydrous cobalt(II) chloride. State the colour change observed.
Choose the formula of the hydrated compound formed in this chemical test from the options below:
The physical test involved measuring a physical property of the liquid. State a suitable physical property and its value for pure water at standard pressure.
Hydrogen was historically used to fill airships and balloons. State the property of hydrogen that makes it suitable for this purpose.
Helium is now used instead of hydrogen. State the property of helium that makes it safer to use than hydrogen.
Write a chemical equation, including state symbols, to show the physical process that occurs when oxygen gas is liquefied.
