Water Hardness
The 2 main ions that contribute to water hardness
Calcium (Ca²⁺) and magnesium (Mg²⁺)
A method where a precipitate is isolated, purified, dried, and massed to quantify an analyte
The chemical formula for sodium carbonate, used in water softening
Na₂CO₃
What is the balanced equation for the reaction between CaCl₂ and Na₂CO₃?
CaCl₂(aq) + Na₂CO₃(aq) → CaCO₃(s) + 2 NaCl(aq)
The most important step you take before you begin an experiment
Put goggles on
The primary problem caused by hard water in household appliances
Scale build up, which reduces efficiency
The precipitate formed in the hard water lab during gravimetric analysis
Calcium carbonate (CaCO₃)
The reason sodium carbonate is used to soften water
It introduces carbonate ions (CO₃²⁻), which react with calcium ions to form insoluble calcium carbonate
The role of sodium carbonate in the hard water experiment
It reacts with calcium ions to form calcium carbonate precipitate
The reason it is important to rinse the precipitate after filtration
To remove impurities
The chemical reaction that leads to formation of scale in pipes
Ca²⁺ + CO₃²⁻ → CaCO₃ (calcium carbonate precipitate)
Gravity and vacuum
The types of ions exchanged in a water softener
Calcium (Ca²⁺) and magnesium (Mg²⁺) ions are exchanged for sodium (Na⁺) ions.
The way CO₂ in the atmosphere contributes to water hardness
CO₂ dissolves in water, dissociates into carbonate (CO₃²⁻) ions, leading to calcium carbonate formation
The reason distilled (deionized) water is used to rinse the precipitate in the hard water lab
To eliminate the possibility of carbonate ions reacting with ions in regular water
It forms insoluble soap scum, making soap less effective.
The purpose of gravimetric analysis in this lab
To determine the amount of calcium carbonate (CaCO₃) in water samples to measure water hardness in a given sample
The steps you would take to calculate the volume of excess 0.5 M Na2CO3 needed if you are reacting with 0.00800 moles of Ca2+ in 20 mL.
0.00800 moles of Ca2+ --> moles of Na2CO3 using balanced equation --> use molarity to find L of Na2CO3 --> convert to mL --> multiply by 1.2
The reason magnesium ions could interfere with the hard water lab
MgCO3 would form
The correct steps for folding a filter paper
Fold the filter paper in half
Fold it in half again
Tear a small corner off
Open the filter paper into a cone
Place in the funnel
Wet the paper
A way hard water can impact cleaning and laundry
Hard water reduces the effectiveness of soap, leading to soap scum
The reason calcium carbonate can be isolated using gravimetric analysis
It is insoluble in water and forms a solid precipitate that can be collected
Na2CO3 is also known as
Soda ash
The reason excess sodium carbonate is used in the experiment
To ensure that all calcium ions react and precipitate as calcium carbonate
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