# Moles and molar concentration

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##### Intros
###### Lessons
1. Expanding our moles calculations
2. Recap - moles, molar volume and concentration
3. Calculating concentration of a solution
4. Example - calculating concentration
5. Titration, an introduction
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##### Examples
###### Lessons
1. Find the number of moles and concentration of substances used in chemical reactions.
1. Calculate the number of moles in 100 mL of 0.2M HCl $_{(aq)}$
2. Calculate the concentration of a solution of 1.7 litres of water with 0.75 moles of HCl dissolved in it.
3. Calculate the new concentration of this solution when 3.4 extra litres of water are added to the solution.
2. Find the number of moles and use it to find the volume of substances used in chemical reactions.
1. Calculate the number of moles in 120mL of 0.05M H$_2$SO$_{4\; (aq)}$ solution.
2. When H$_2$SO$_4$ and CaCO$_3$ are reacted, CO$_2$ gas is produced. What is the volume of CO$_{2\; (g)}$ produced when 120 mL of 0.1M H$_2$SO$_{4\; (aq)}$ is reacted with an excess amount of CaCO$_3$?
3. What volume of 0.04M HCl $_{(aq)}$ is required to react completely to neutralise 6 g of Mg(OH)$_2$?
3. Find the number of moles and use it to find the molarity of substances used in chemical reactions.
1. In a titration reaction, 32 mL HCl $_{(aq)}$ of unknown concentration reacts with 25 mL of 0.5M NaOH $_{(aq)}$. Calculate the molarity of the hydrochloric acid being analysed.
2. In another titration reaction, it took 14mL of NaOH $_{(aq)}$ of unknown concentration to react with 39 mL of 0.1M H$_3$PO$_{4\; (aq)}$. Calculate the molarity of the NaOH solution used.
4. Find the number of moles and use it to find the quantities of substances used in chemical reactions.
Consider the reaction:
2 Al$_{\;(s)} +$2 NaON$_{\;(aq)} +$2 H$_2$O$_{\;(l)}$→2 NaAlO$_{2\;(aq)} +$3 H$_{2\;(g)}$
1. A student needs to produce 20L of H$_2$ at STP using this reaction. Excess water and aluminium is available to react with 1.5M sodium hydroxide solution. How much sodium hydroxide solution will be required?
2. When repeating the experiment, only 500 mL of 2.2M sodium hydroxide solution is available. How many litres of hydrogen gas can be produced given this limit?