{"articleData":{"id":762,"name":"CP 4 - Investigation of the rates of hydrolysis of halogenoalkanes","description":"An overview of CP 4 - Investigation of the rates of hydrolysis of halogenoalkanes","image":"https://d3nzlfkeryzt6j.cloudfront.net/n1t000i7obbil8crfrpxsfd3dn2c","image_content_type":"image/svg+xml","seo_image":"https://d3nzlfkeryzt6j.cloudfront.net/1etkc5933gw9zyxuphv7uyjlm9gc","chapters":[{"id":2271,"name":"Experimental aim ","slug":"experimental-aim","blocks":[{"id":18119,"block_type":"Tip","block":{"button_label":null,"display_type":"no_attachments","id":8056,"image_a_alt_text":null,"image_b_alt_text":null,"name":"1_PSC_05_028","text_content_a_html":"

In Edexcel Core Practical 4: Investigation of the rates of hydrolysis of halogenoalkanes the rates are determined for primary, secondary and tertiary halogenoalkanes along with chloro-, bromo-, and iodoalkanes

The time taken for the precipitate to appear is recorded and used to compare the reactivity of different halogenoalkanes.

In Edexcel core practical 4: Investigate the hydrolysis of halogenoalkanes, there are several important safety requirements to be aware of (beyond normal lab practice such as wearing goggles).

Halogenoalkanes are flammable and harmful.
Ethanol is flammable – avoid naked flames.
Silver nitrate is corrosive.

","text_content_b_html":null,"text_content_c_html":null,"text_content_d_html":null,"text_content_e_html":null,"text_content_f_html":null,"image_attribution_html":null,"saved_count":0,"image_attachment_a":null,"image_attachment_a_dark":null,"image_attachment_b":null,"image_attachment_b_dark":null,"image_width":null,"image_height":null,"image_content_type":null,"file_attachment":null}}]},{"id":2273,"name":"Method","slug":"method","blocks":[{"id":18120,"block_type":"Tip","block":{"button_label":null,"display_type":"image","id":8057,"image_a_alt_text":"Diagram titled 'Experimental Method Edexcel Core Practical 4' with five steps. Step 1: 'Set a water bath at around 50°C.' Image shows a water bath set to 50°C. Step 2: 'Add 5 cm³ of ethanol to three labelled test tubes.' Illustration of test tubes with ethanol and halogenoalkanes: 1-chlorobutane, 1-bromobutane, or 1-iodobutane. Test tubes are in a rack. Step 3: 'Add 5 cm³ of silver nitrate solution to three clean test tubes.' Illustration of a dropper labeled 'AgNO3(aq)' adding solution to test tubes. Step 4: 'Wait for the halogenoalkane–ethanol solutions to reach temperature then add the silver nitrate solution to them and replace the bung.' Shows test tubes with different precipitates: white, cream, yellow, labeled 'AgCl', 'AgBr', 'AgI'. Stopwatch reads '00:00 s'. Step 5: 'Repeat the experiment for 2-bromobutane and 2-bromo-2-methylpropane. Record your results in a table.' Table lists halogenoalkanes and 'Time taken for precipitate to form (seconds)': 1-iodobutane, 1-bromobutane, 1-chlorobutane, 2-bromobutane, 2-bromo-2-methylpropane.","image_b_alt_text":null,"name":"1_PSC_05_029","text_content_a_html":"

Experimental method for Edexcel Chemistry Core Practical 4

","text_content_b_html":"","text_content_c_html":null,"text_content_d_html":null,"text_content_e_html":null,"text_content_f_html":null,"image_attribution_html":"","saved_count":0,"image_attachment_a":"https://d3nzlfkeryzt6j.cloudfront.net/5t7sw220t08sif8cjw5j486ah45c","image_attachment_a_dark":"https://d3nzlfkeryzt6j.cloudfront.net/1rjtil30ab90isrbriivfflmliik","image_attachment_b":null,"image_attachment_b_dark":null,"image_width":1056,"image_height":2594,"image_content_type":"image/png","file_attachment":null}}]},{"id":2274,"name":"Practical pitfalls ","slug":"practical-pitfalls","blocks":[{"id":17465,"block_type":"Tip","block":{"button_label":null,"display_type":"do_dont_image","id":3613,"image_a_alt_text":"A laboratory setup featuring a beaker filled with blue liquid, supported by a wire gauze on a stand. A thermometer is inserted into the beaker, and the setup is heated by a Bunsen burner with a gas hose.","image_b_alt_text":"A test tube with blue liquid is being heated over a flame from a Bunsen burner.","name":"1_PSC_04_085","text_content_a_html":"

Be sure to heat the test tubes carefully when the contents are temperature sensitive.

","text_content_b_html":"","text_content_c_html":"

Use a water bath for heating test tubes. A water bath provides even, controlled heating, reducing the risk of glassware breaking or the contents overheating. Maximum temperature is capped at the boiling temperature of water.

","text_content_d_html":"

Heat test tubes directly over a Bunsen burner. Direct flame can cause rapid temperature changes.

","text_content_e_html":null,"text_content_f_html":null,"image_attribution_html":null,"saved_count":0,"image_attachment_a":"https://d3nzlfkeryzt6j.cloudfront.net/3xhsqt8fl72fg92hikkr6c1q4hqc","image_attachment_a_dark":"https://d3nzlfkeryzt6j.cloudfront.net/175wu1lsw4chhi2y3fvyd8ar3ax5","image_attachment_b":"https://d3nzlfkeryzt6j.cloudfront.net/vv980nzn65wxhmgadxe35f7sqwmr","image_attachment_b_dark":"https://d3nzlfkeryzt6j.cloudfront.net/wcngpmlx03096mcj6usp74z43iwu","image_width":512,"image_height":512,"image_content_type":"image/png","file_attachment":null}}]},{"id":2275,"name":"Analysis and evaluation","slug":"analysis-and-evaluation","blocks":[{"id":18121,"block_type":"Tip","block":{"button_label":null,"display_type":"no_attachments","id":8058,"image_a_alt_text":null,"image_b_alt_text":null,"name":"1_PSC_05_030","text_content_a_html":"

The rate of hydrolysis of the halogenoalkane relates to the strength of the carbon-halide bond. The stronger the bond, the slower the rate of the reaction.

The quicker the formation of the precipitate, the faster the substitution reaction occurs.

Therefore, it is possible to determine the order of carbon-halide bond strength by comparing the times obtained in the experiment.

On this page

Experimental aim

Safety

Method

Practical pitfalls

Analysis and evaluation