All Solutions
Page 258: Review
The coefficient of zinc sulfide in the balanced chemical equation is $2$.
Sulfur dioxide is SO$_2$, this implies that each molecule of sulfur dioxide has 1 sulfur atom and 2 oxygen atoms.
The coefficient of oxygen gas in the balanced chemical equation is $3$.
Two reactants, zinc sulfide and oxygen gas are shown here.
There are 2 molecules of zinc sulfide and 3 molecules of oxygen gas in the balanced chemical equation, therefore there are $2+3=5$ reactant molecules in this equation.
Zinc sulfide and zinc oxide are solids while oxygen and sulfur dioxide are gases at r.t.p.
Hydrocarbons produce a yellow flame and a sooty residue when they are burnt in insufficient supply of air. Because of the insufficient supply of air (oxygen) the hydrocarbon fails to burn completely and yields carbon monoxide responsible for the yellow flame and unburnt hydrocarbon that appears as the sooty residue.
This type of combustion is called incomplete combustion. This, as the name suggests implies that the hydrocarbon has failed to burn completely to yield its maximum energy and because of this it can be said that the hydrocarbon has been wasted as unburnt hydrocarbon.
A two element reaction is a synthesis reaction where the two elements combine together to form a compound.
A two compound reaction is a double displacement reaction where the ions of the two compounds are swapped to form new products.
A reaction involving oxygen and a fuel is a combustion reaction where the fuel burns with oxygen gas to form carbon dioxide and water vapor.
A reaction involving only one compound is a decomposition reaction where the compounds breaks down in the presence of heat to simpler compounds or elements.
A reaction involving an element and a compound is a single displacement reaction where the atoms of the element replace the ions of the compound to form a new compound. The ions replaced convert to their element form.
State symbol (aq) is the abbreviation of the word aqueous which means that the ions of the electrolyte are free to move in its ionic form. This is usually achieved by dissolving the electrolyte in water. State symbol (l) is the abbreviation of the word liquid which implies that the element/compound is in its molten/liquid state. For example NaCl$_{(l)}$ will mean that sodium chloride is in its molten/liquid state. where by NaCl$_{(aq)}$ means that the salt is dissolved in water.
The oxygen gas produced will escape from the test tube. This can be tested by bringing a glowing splinter near the opening of the test tube. The glowing splinter will rekindle.
The completion of the reaction will be observed by the stopping of the escape of oxygen gas from the test tube.
The mass of the contents of the test tube will decrease as the reaction proceeds. This is because hydrogen peroxide is being decomposed to water and oxygen gas. Oxygen gas will escape from the test tube decreasing the contents and hence the mass of the test tube.
Balanced chemical equation:
$$
mathrm{2K_2O longrightarrow 4K+O_{2}}
$$
This is a decomposition reaction.
Balanced chemical equation:
$$
mathrm{2Na+I_2longrightarrow 2NaI}
$$
This is a synthesis reaction.
Balanced chemical equation:
$$
mathrm{Cu(NO_3)_2 +2NaOHlongrightarrow Cu(OH)_2+2NaNO_3}
$$
This is a double displacement reaction.
Balanced chemical equation:
$$
mathrm{2KClO_3 longrightarrow 2KCl+3O_{2}}
$$
This is a decomposition reaction.
Balanced chemical equation:
$$
mathrm{Ca(NO_3)_2 +2HBrlongrightarrow CaBr_2+2HNO_3}
$$
This is a double displacement reaction.
Balanced chemical equation:
$$
mathrm{Sn(OH)_2 longrightarrow SnO+H_2O}
$$
This is a decomposition reaction.
Balanced chemical equation:
$$
mathrm{P_4+6N_2Olongrightarrow P_4O_6+6N_2}
$$
This is a singe displacement reaction.
Balanced chemical equation:
$$
mathrm{3Fe+Al_2(SO_4)_3longrightarrow 3FeSO_4+2Al}
$$
This is a singe displacement reaction.
Balanced chemical equation:
$$
mathrm{2AlCl_3+3Na_2CO_3 longrightarrow Al_2(CO_3)_3+6NaCl}
$$
This is a single displacement reaction.
Balanced chemical equation.
$$
mathrm{2C_3H_{6} + 9O_{2} longrightarrow 6CO_{2} + 6H_2O_{}}
$$
This is a combustion reaction.
Balanced chemical equation:
$$
mathrm{2NaN_{3(s)} longrightarrow 3N_{2(g)}+2Na_{(s)}}
$$
This is a decomposition reaction.
Balanced chemical equation:
$$
mathrm{6Na_{(s)}+Fe_2O_{3(s)} longrightarrow 3Na_{2}O_{(s)}+2Fe_{(s)}}
$$
This is a single displacement reaction.
Balanced chemical equation:
$$
mathrm{Na_2O_{(s)}+2CO_{2(g)}+H_2O_{(g)} longrightarrow 2NaHCO_{3(s)}}
$$
This is a decomposition reaction.
Word equation:
$$
text{iron + oxygen gas}longrightarrow text{ion(III) oxide + energy}
$$
Balanced chemical equation:
$$
mathrm{4Fe_{(s)} + 3O_{2(g)} longrightarrow 2Fe_{2}O_{3(s)}}
$$
Vacuum out all air in an enclosed chamber containing iron metal of known mass. Gradually introduce oxygen gas of known mass in this chamber via a gas-syringe. At the end of the reaction, weigh the mass of iron(III) oxide formed. Its mass should be equal to the sum of the mass of iron metal and oxygen gas used to convert it to iron(III) oxide.
According to the law of conservation of masses, the total mass of the products is equal to the total mass of the reactants, therefore the amount of hydrogen gas produced must be $52.6+2.5-54.8=55.1-54.8=0.3$ grams.
The mass the products is equal to the mass of the reactants therefore law of conservation of masses is not violated.
Option 1 is a healthier option but it is costly.
Option 2 is the economical choice here but it is detrimental to health as exposure to lead adversely affects brain development in children which is a life long disability.
Being the principal of the school and being responsible for the students and staff under my care, I would have chosen option 1 of providing bottled water because it is healthy as opposed to the water supplied to the school.
The first step of this reaction involves a $color{#c34632}text{synthesis}$ reaction between impure nickel and carbon monoxide to form nickel carbonyl.
The second step of this reaction involves a $color{#c34632}text{decomposition}$ reaction where nickel carbonyl breaks down to form pure nickel and carbon monoxide.
Reactions must be carried out in airtight chambers to prevent the escape of carbon monoxide as it is a poisonous gas long exposures to which can even be fatal. Nickel carbonly is also the most of nickel compounds. Exposure to this affects the human head, disturbs sleep patterns, causes irritability and damages the respiratory system.
Balanced chemical equation:
$$
mathrm{NH_4NO_{3(s)} longrightarrow N_{2}O_{(g)} + 2H_2O_{(l)}}
$$
