ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

GCSE Chemistry - Qualitative Analysis

Updated on November 19, 2012

Cations and Anions Definitions

Cation: A positive ion (an atom that has lost electrons).
Anion: A negative ion (an atom that has gained electrons).

Analysing Cations:

Flame Test results:

A flame test is a test that is used to determine what an unknown metal ion is. The heat of the flame 'excites' the metals ions, causing them to emit visible light. The colour of the visible light is what shows us what metal ion is present.


Calcium - Yellow-red flame.
Lithium – Red flame.
Sodium – Orange flame.
Copper - Green-blue flame.
Potassium – Lilac flame.
Barium - Pale green flame.

Add sodium hydroxide to the 'mystery solution', metal hydroxides are insoluble and will precipitate out of the solution. Some of these metal hydroxides have characteristic colours, then you can tell which metal is in the compound.

Calcium – White precipitate of calcium hydroxide is formed.
Magnesium – White precipitate of magnesium hydroxide is formed.
Aluminium – White precipitate of aluminium hydroxide is formed.
Iron(II) – Green precipitate of iron(II) hydroxide is formed.
Iron(III) - Brown precipitate of iron(III) hydroxide is formed.
Copper – Pale blue precipitate of copper (II) Hydroxide is formed.

Analysing Anions:

The 'Silver Nitrate Test' for halide ions (chloride, bromide and iodide):

Add a few drops of silver nitrate to your 'mystery compound', this is go get rid of any carbonate or sulphite ions before the test. Then add a few drops of silver nitrate solution. Precipitates of silver chloride, silver bromide and silver iodide form. You can tell which ion is present because the different precipitates have the following characteristic colours:

Chloride – White precipitate
Bromide – Cream precipitate
Iodide – Yellow precipitate

To test for sulphate ions, put some of a solution of the compound that you are testing into a test tube and then add few drops of dilute hydrochloric acid (again, this is to get rid of any sulphite or carbonate ions). Then add a few drops of barium chloride solution. If a sulphate ion is present a white precipitate of barium sulphate will form.

To test for sulphites SO32-- Add hydrochloric acid to solution that you want to test. The sulphites then react with the hydrogen to give sulphur dioxide and water. Sulphur dioxide turnsdamp potassium dichromate paper (VI) from orange to green.

To test for carbonate ions
add a few drops of dilute hydrochloric acid to the test substance. Bubbles of carbon dioxide gas are given off if carbonate ions are present.


Comments

    0 of 8192 characters used
    Post Comment

    No comments yet.

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, hubpages.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: "https://hubpages.com/privacy-policy#gdpr"

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)