Molar Concentrations
Overzicht
A technician hands you two identical bottles. Both hold a colourless liquid, both are labelled dilute hydrochloric acid, and both look exactly the same through the glass. One of them would sting for a second on your skin. The other would ruin your laboratory coat. Nothing you can see, smell or weigh from the outside separates them, because what differs is not what the liquid is made of but how tightly the acid is packed into the water. That quantity has a name, a unit and an equation, and without it a bottle of solution is chemically anonymous.
This lesson gives you the number and the method for measuring it. You will learn why chemists count solutions in moles rather than grams, why a careful worker deliberately throws the first result of an experiment away, and how a single drop from a burette can settle a question that no amount of looking at the bottle ever could. At the end you will meet a shortcut that lets you count the particles in a gas simply by measuring the space they occupy, no balance required.
Doelstellingen
- The concentration of a solution is related to the mass of the solute (in terms of number of moles) and the volume of the solution. The concentration of a solution is calculated as follows: Concentration (mol/dm3) = number of moles/volume of solution (in dm3).
- The volumes of acid and alkali solutions that react with each other can be measured by titration using a suitable indicator. Students should be able to carry out titrations using strong acids and strong alkalis only (sulfuric, hydrochloric and nitric acids only). Required practical: Establish the concentration of an unknown strong acid through titration with a strong base.
- If the concentration of one of the reactants is known, the results of a titration can be used to find the concentration of the other reactant. Students should know how to carry out a titration and be able to calculate the chemical quantities in titrations involving concentrations in mol/dm3 and in g/dm3.
- The molar gas volume at room temperature and pressure is assumed to be 24 dm3. Students are expected to be able to calculate the number of moles or the volume of gas in a reaction.
Mindmap
Dit onderwerp is in kaart gebracht zodat je ziet hoe de ideeen samenhangen.
Open de mindmap in de app
Flashcards
Snelle geheugentraining op wat bij dit onderwerp getoetst wordt.
Oefen deze kaarten in de app
Lesnotitie
Volledige lesnotitie beschikbaar in de Green Bridge-app
Installeer de Green Bridge CBT-app op je telefoon of computer voor de volledige IGCSE-bibliotheek: examens uit voorgaande jaren, correctiemodellen, mindmaps, flashcards en audiolessen.
Lesevaluatie
Gefeliciteerd met het voltooien van de les op Molar Concentrations. Nu je de sleutelconcepten en ideeën, het is tijd om uw kennis op de proef te stellen. Deze sectie biedt een verscheidenheid aan oefeningen vragen die bedoeld zijn om uw begrip te vergroten en u te helpen uw begrip van de stof te peilen.
Je zult een mix van vraagtypen tegenkomen, waaronder meerkeuzevragen, korte antwoordvragen en essayvragen. Elke vraag is zorgvuldig samengesteld om verschillende aspecten van je kennis en kritisch denkvermogen te beoordelen.
Gebruik dit evaluatiegedeelte als een kans om je begrip van het onderwerp te versterken en om gebieden te identificeren waar je mogelijk extra studie nodig hebt. Laat je niet ontmoedigen door eventuele uitdagingen die je tegenkomt; beschouw ze in plaats daarvan als kansen voor groei en verbetering.
- What is 500 cm3 expressed in dm3? A. 0.05 dm3 B. 0.5 dm3 C. 5 dm3 D. 5000 dm3 Answer: B
- A solution contains 0.100 mol of solute in 250 cm3 of solution. What is its concentration? A. 0.025 mol/dm3 B. 0.400 mol/dm3 C. 2.50 mol/dm3 D. 25.0 mol/dm3 Answer: B
- A solution of sodium hydroxide has a concentration of 0.500 mol/dm3. The relative formula mass of NaOH is 40. What is the concentration in g/dm3? A. 0.0125 g/dm3 B. 8.00 g/dm3 C. 20.0 g/dm3 D. 80.0 g/dm3 Answer: C
- What volume is occupied by 2.0 mol of oxygen gas at room temperature and pressure? A. 12 dm3 B. 24 dm3 C. 48 dm3 D. 12 000 dm3 Answer: C
- A student records four titres: 25.30 cm3, 24.45 cm3, 24.50 cm3 and 24.40 cm3. What is the correct mean titre? A. 24.40 cm3 B. 24.45 cm3 C. 24.66 cm3 D. 25.30 cm3 Answer: B
Maak deze vragen in de app
Maak deze vragen in de app
Aanbevolen Boeken
Verder leren met open bronnen
-
Leerboekparagraaf
Reaction Stoichiometry
Explain the concept of stoichiometry as it pertains to chemical reactions
"Chemistry: Reaction Stoichiometry" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/chemistry/pages/4-3-reaction-stoichiometry. Access for free at https://openstax.org/books/chemistry/pages/1-introduction
-
Leerboekparagraaf
Stoichiometry of Gaseous Substances, Mixtures, and Reactions
Use the ideal gas law to compute gas densities and molar masses
"Chemistry: Stoichiometry of Gaseous Substances, Mixtures, and Reactions" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/chemistry/pages/9-3-stoichiometry-of-gaseous-substances-mixtures-and-reactions. Access for free at https://openstax.org/books/chemistry/pages/1-introduction
Gepubliceerd door andere organisaties onder open licenties, vermeld zoals zij vragen. Links openen hun websites.
Oefen Proefexamenvragen
Wilt u proefexamenvragen over Molar Concentrations oefenen? Download de Green Bridge CBT-app voor toegang tot proefexamenvragen en volledige oefentoetsen over dit onderwerp.
Download de app in de Google Playstore
Alles wat je nodig hebt om uit te blinken in JAMB, WAEC en NECO.
