According to the experiment in the third reaction, CuS crystals go white and droplets of H2O form on the sides of the test tube. The CuS crystals have lost their H2O of crystalization. This process is called "Efflorescene" this is because when some hydrated salt when exposed to atmosphere, they lose part or all their water of crystalization.

<p>The aim of this optional experiment is to investigate three <a data-lesson="reactions-2" data-subject="chemistry" data-tutorial="metals-metalloids-nonmetals" href="https://app.ulearngo.com/chemistry/metals-metalloids-nonmetals/reactions-2">reactions</a> to learn about <a data-lesson="elements" data-subject="chemistry" data-tutorial="classification-of-matter" href="https://app.ulearngo.com/chemistry/classification-of-matter/elements">elements</a> and compounds.</p>
<div class="ns-school-emp">
<h2>Experiment: Investigating Elements and Compounds</h2>
<div class="ns-school-defn">
<section class="activity">
<h3>Aim</h3>
<p>To investigate three reactions to learn about elements and compounds.</p>
</section>
<section class="activity">
<h3>Apparatus</h3>
<ul>
<li>
<p>Cal-C-Vita tablet</p>
</li>
<li>
<p>test tubes</p>
</li>
<li>
<p>Bunsen burner</p>
</li>
<li>
<p>rubber stopper</p>
</li>
<li>
<p>delivery tube</p>
</li>
<li>
<p>lime water (a saturated solution of \(\text{Ca}(\text{OH})_{2}\))</p>
</li>
<li>
<p>candle</p>
</li>
<li>
<p>matches</p>
</li>
<li>
<p>copper sulfate (\(\text{CuSO}_{4}·5\text{H}_{2}\text{O}\))</p>
</li>
<li>
<p>zinc metal</p>
</li>
<li>
<p>hydrochloric <a data-lesson="nonmetal-oxyacids-and-their-salts" data-subject="chemistry" data-tutorial="metals-metalloids-nonmetals" href="https://app.ulearngo.com/chemistry/metals-metalloids-nonmetals/nonmetal-oxyacids-and-their-salts">acid</a> (\(\text{HCl}\))</p>
</li>
</ul>
<p><img alt="3904dd415cc5857b8ca741e417a5b349.png" src="https://data.ulearngo.com/assets/708a639f-6e37-4f7f-a8ae-32e49abc4a6f"/></p>
<p><img alt="edd9e88b027819dece7b045b27aa79ee.png" src="https://data.ulearngo.com/assets/9f561c5d-97ce-4b09-b400-598f500c9691"/></p>
<p><img alt="ad5ea26991c8afae2fd01f3d1f795ddb.png" src="https://data.ulearngo.com/assets/1badbace-94de-475f-a285-c2948b57944d"/></p>
</section>
<section class="activity">
<h3>Method</h3>
<p><em>Reaction 1</em></p>
<ol>
<li>
<p>Pour clear <a data-lesson="lime" data-subject="chemistry" data-tutorial="chemistry-real-world" href="https://app.ulearngo.com/chemistry/chemistry-real-world/lime">lime</a> water into a <a data-lesson="reaction-rates-in-analysis-test-strips-for-urinalysis" data-subject="chemistry" data-tutorial="chemical-kinetics" href="https://app.ulearngo.com/chemistry/chemical-kinetics/reaction-rates-in-analysis-test-strips-for-urinalysis">test</a> tube.</p>
</li>
<li>
<p>Into a second test tube place a Cal-C-Vita tablet. Cover the tablet with water and immediately place a stopper and delivery tube into the test tube.</p>
</li>
<li>
<p>Place the other end of the delivery tube into the lime water in the first test tube. Allow it to bubble for 1-2 minutes.</p>
</li>
<li>
<p>Now remove the stopper from the second test tube and hold a lit candle at the mouth of the test tube.</p>
</li>
<li>
<p>Record your observations.</p>
</li>
</ol>
<p><em>Reaction 2</em></p>
<ol>
<li>
<p>Place a few drops of <a data-lesson="chemical-reduction" data-subject="chemistry" data-tutorial="metals-metalloids-nonmetals" href="https://app.ulearngo.com/chemistry/metals-metalloids-nonmetals/chemical-reduction">zinc</a> metal in a test tube and cover the <a data-lesson="limiting-reagents" data-subject="chemistry" data-tutorial="quantitative-aspects-chemical-change" href="https://app.ulearngo.com/chemistry/quantitative-aspects-chemical-change/limiting-reagents">pieces</a> with dilute hydrochloric acid.</p>
</li>
<li>
<p>Record your observations.</p>
</li>
<li>
<p>Now hold a burning match in the mouth of the test tube and observe what happens.</p>
</li>
</ol>
<p><em>Reaction 3</em></p>
<ol>
<li>
<p>Place a spatula full of <a data-lesson="isolation-of-copper" data-subject="chemistry" data-tutorial="transition-metals" href="https://app.ulearngo.com/chemistry/transition-metals/isolation-of-copper">copper</a> sulfate crystals into a test tube and <a data-lesson="calorimetry" data-subject="chemistry" data-tutorial="thermochemistry" href="https://app.ulearngo.com/chemistry/thermochemistry/calorimetry">heat</a> the tube over a Bunsen burner.</p>
</li>
<li>
<p>Record your observations.</p>
</li>
</ol>
</section>
<section class="activity">
<h3>Discussion and conclusion</h3>
<p>In the first reaction the lime water goes milky due to the presence of carbon dioxide. (Lime water can be used to detect carbon dioxide gas.) The carbon dioxide gas comes from the sodium bicarbonate (\(\text{NaHCO}_{3}\)) in the tablet. When you hold the candle over the test tube, the carbon dioxide snuffs out the candle flame.</p>
<p>In the second reaction bubbles of <a data-lesson="hydrogen-reactions" data-subject="chemistry" data-tutorial="metals-metalloids-nonmetals" href="https://app.ulearngo.com/chemistry/metals-metalloids-nonmetals/hydrogen-reactions">hydrogen</a> gas form. Zinc reacts with the hydrochloric acid to form zinc chloride and hydrogen gas.</p>
<p>In the third reaction the copper sulfate crystals go white and droplets of water form on the sides of the test tube. The copper sulfate crystals have lost their water of crystallisation.</p>
</section>
</div>
</div>
<section></section>

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Investigating Elements and Compounds

Chemistry generally explores the substances of which matter is composed, the investigation of their properties and reactions, and the use of such reactions to form new substances. 

Chemistry

Explore the essential ideas in chemistry, including the scientific method, laboratory skills and safety, states of matter, measurement uncertainty, models of the atom, electronic configurations, and more.


Investigating Elements and Compounds

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