Acid/Base Basics For instance, 30 mL of 1.00 M NaOH is needed to titrate 60 mL of an HCl solution. The concentration of HCl needs to be determined. At the eqivalence point: Beautiful Reactions Precipitation Chemical Garden Color Change Acid vs Base Bases are the chemical opposite of acids. Acids are defined as compounds that donate a hydrogen ion (H+) to another compound (called a base). Traditionally, an acid (from the Latin acidus or acere meaning sour) was any chemical compound that, when dissolved in water, gives a solution with a hydrogen ion activity greater than in pure water, i.e. a pH less than 7.0. Correspondingly, a base was any compound that, when dissolved in water, gives a solution with a hydrogen ion activity lower than that of pure water, i.e. a pH higher than 7.0 at standard conditions. A soluble base is also called an alkali.
The Colours & Chemistry of pH Indicators Most of us, chemists or otherwise, have probably come across pH indicators at one point or another. I’d be surprised if there’s anyone out there who hasn’t, back in school, carried out the standard experiment of adding universal indicator to a variety of household liquids to identify them as acidic or alkaline. You might not be aware of the large range of different indicators that can be used to identify varying pHs, however, or the reasons behind the colour changes observed. Firstly, it might seem a little odd that different indicators are even required, considering that universal indicator gives us a broad range of colours across the pH scale. However, universal indicator gives us a range of gradual colour changes, across a range of pH, rather than clearer ones at more specific pH ranges. When trying to completely react a certain amount of acid with an alkali, we want to know when we’ve added the exactly correct amount of alkali, for instance – this is called the equivalence point.
Chemical Reactions Posters – Part I Click to enlarge Recently, some of my classes have been revising types of chemical reactions, which inevitably set me thinking about how to represent them visually in an easy to understand way. These are the first few posters I’ve come up with – each has a large icon representative of the reaction type, as well as a short description of the reaction, and an example. Hoping to add a few more over the next few days!
How To Memorize Things Quickly & Effectively What separates you from someone that can memorize π (pi) to the 100th decimal? It’s not natural ability; it’s technique and practice. In this tutorial, I will teach you how to master memorization and change your life. Table Of Contents Chunking | Break the information up into smaller chunks and re-categorize it.Spaced Repetition | Exploit the spacing effect by using an SRS flashcard application.Understand Memory | Learn the 11 properties that determine the difficulty of a given piece of information.Preparation | Avoid music with lyrics.
‘Poisonous’ Poinsettia pH Indicators I’m making pH indicator paper with some of my classes this week, using the coloured leaves of red poinsettia plants, which set me thinking about the chemistry behind why these plants can be used as indicators. Poinsettias have a reputation for being poisonous – a claim that is in fact entirely unfounded. A quick google search will reveal that the myth of poisonous poinsettias potentially originates from a ingestion of poinsettia leaves being mistakenly attributed as the cause of poisoning of an american child in 1919. Not being poisonous obviously isn’t quite the same as being edible, and eating poinsettia leaves can potentially cause stomach pain and vomiting – but there have been no recorded deaths as a result of the plant. As its leaves also have a reportedly ‘indescribably awful’ taste, few could probably bear more than a nibble. As any secondary school science teacher will know, it’s not just poinsettias that can be used to fashion rudimentary indicator solutions.
Chemical Reactions Posters – Part II Click to enlarge Here’s the second part of the Chemical Reactions posters, this time featuring condensation, hydrolysis, displacement, oxidation, and reduction reactions. Click the image above to enlarge and read the text, or, as previously, I’ve included the text separately in the post below. Print-friendly versions are again available to download at the foot of the page. Condensation Reactions: A condensation reaction is one in which two molecules combine to form a larger molecule, with the loss of a small molecule.
Middle Level Science (Grades 5–8) Subtest 1 Sample Items 1. Radioactive isotope labeling using elements such as carbon and nitrogen has contributed most significantly to biology by facilitating the: creation of diffraction images for deducing the chemical structure of nucleotides. use of spectral analysis to determine the chemical composition of biomolecules. analysis of the movement of molecules during biochemical processes. ability to physically separate large macromolecules such as proteins from the cell cytoplasm.
The Elephant's Toothpaste Experiment - ScienceBob.com You will need A clean 16 ounce plastic soda bottle1/2 cup 20-volume hydrogen peroxide liquid (20-volume is a 6% solution, ask an adult to get this from a beauty supply store or hair salon)1 Tablespoon (one packet) of dry yeast3 Tablespoons of warm waterLiquid dish washing soapFood coloringSmall cupSafety goggles NOTE: The foam will overflow from the bottle, so be sure to do this experiment on a washable surface, or place the bottle on a tray. Chemistry 1102: Indicators and the pH Scale Instructions Before viewing an episode, download and print the note-taking guides, worksheets, and lab data sheets for that episode, keeping the printed sheets in order by page number. During the lesson, watch and listen for instructions to take notes, pause the video, complete an assignment, and record lab data. See your classroom teacher for specific instructions. Note Taking Guide
Chemistry 1103: Neutralization Reactions Instructions Before viewing an episode, download and print the note-taking guides, worksheets, and lab data sheets for that episode, keeping the printed sheets in order by page number. During the lesson, watch and listen for instructions to take notes, pause the video, complete an assignment, and record lab data. See your classroom teacher for specific instructions. Note Taking Guide Neutralization Reactions Lab