This is the first time learners are presented to acids and also bases. The strategy is to start from the known and introduce the topic through learner"s experience with day-to-day acids and bases. We will also an initial look at exactly how we suffer acids and also bases in foods. This web links to Life and Living and the senses. We will then look at acids and also bases in the laboratory and the straightforward properties that acids, bases and neutrals. They will certainly look at acids and bases again in Gr. 9 in more detail, additionally covering the pH scale, and also the reactions of acids and also bases.

You are watching: What does a base taste like

3.1 Tastes of building materials (1 hour)

Tasks

Skills

Recommendation

Activity: have actually a look in ~ your very own tongue

Observing, comparing

Suggested

3.2 properties of acids, base and also neutrals (2 hours)

Tasks

Skills

Recommendation

Activity: True or false?

Accessing and also recalling information

Suggested

Activity: Acids and also bases in ours homes

Accessing and also recalling information, observing, comparing, sorting and classifying

CAPS suggested

3.3 Acid-base indicators (3 hours)

Tasks

Skills

Recommendation

Activity: Preparing and also testing red cabbage juice with acid and base

Following instructions, handy skills, observing, comparing

Suggested

Activity: make red cabbage indicator paper

Following instructions, helpful skills

Optional

Investigation: how does litmus respond come acids and also bases?

Hypothesising, act investigation, record information, comparing, interpreting information

CAPS suggested

Investigation: Is red cabbage paper suitable together acid-base indicator?

Doing investigation, record information, interpreting information

Optional


which tastes can we feeling with ours tongues? exactly how does our feeling of taste ensure ours survival? What space the distinct properties of: acids; bases; neutral substances? Which family members substances room (or contain): acids; bases; neutral substances? How can we tell if other is one acid, a base or a neutral substance?
What carry out you know around acids? would you touch an acid? have actually you ever tasted one acid? carry out you think that is possible to taste an mountain without burning your tongue? What carry out you think it would certainly feel like when an acid burned your tongue?

prior to we talk much more about acids, let us an initial examine the human tongue. The is a most fascinating organ, and plays an important role in our sense of taste.


Tastes the substances


flavour feeling taste sprout chemoreceptor savoury instinct tongue map
What is her favourite food? What carry out you like most about your favourite food? friend will probably say that you just LOVE the taste that it! The taste of ours favourite foodstuffs make united state feel good. Just how do we taste ours food?

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we taste food through tiny frameworks on our tongues! look in the mirror, and stick out your tongue. Look because that small, ring bumps. These are referred to as papillae. Many of them contain taste buds. The taste buds space very little structures which have actually sensitive hairs. The chemistry in the food that you eat dissolve into your saliva in solution. The chemicals climate stimulate the small hairs within the tastebuds and also turn these signals into impulses. These impulses take trip to the brain allowing united state to suffer the sensation of taste.


Insects have actually the many highly occurred sense that taste. They have actually taste organs on their feet, antennae, and also mouthparts.


learners will study the nervous system in an ext detail in Gr. 9 Life and Living, and in Life scientific researches if they lug on through the subject in Gr. 10. For now, this is just amazing information around how we taste foods and also distinguish between different tastes.


us have more than 10 000 taste buds in our mouth. You even have taste buds on the roof of her mouth.


have a look in ~ your own tongue
together a homework exercise, learners can do the complying with activity. Otherwise, if you have actually some mirrors available in the classroom, learners have the right to have a look at at your tongues. If you execute this in class, try bringing some lemons to class for learner to taste and also then define their experiences.


MATERIALS:

mirror pencil sugar water lemon juice

INSTRUCTIONS:

look in the mirror at your tongue. Stick it the end as far you can and shot to see the papillae. Room they larger in part areas?

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have you tasted a lemon before? Close her eyes and imagine biting into a slice of lemon. Can you explain the experience? What walk the lemon taste like? Sweet, sour, braided or bitter?


Sour


If you have sugar solution and lemon juice accessible in the class, taste these various substances. See if you deserve to identify where on her tongue girlfriend taste the two various tastes.


Your tongue have the right to only sense 4 flavours

You deserve to only sense four different tastes with your tongue. Can you name them?


Sweet, sour, bitter and salt.


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The tongue map. The four main tastes the are many common, room sweet, sour, salt and also bitter. This tastes combine to consist of the various flavours of our foods.


A flavour is a mix of tastes and smells.


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how would girlfriend classify the taste the apples? Sweet or sour? Bitter? perhaps a combination?
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Many world really gain the sour-salty taste that salt and also vinegar chips! over there is a great reason for why us like certain tastes, however not others.


Our sense of taste protects us

simply as us like and seek out foods that taste good, our body have also been programmed to stop food with strong bitter or cake tastes. This help to protect us versus poisons, which often have a solid bitter taste. "Bitter" is also the straightforward taste that our tongues are many sensitive to. Spoiled food regularly tastes sour and also it may also have a poor smell. Ours instinct will certainly be to protect against it, i beg your pardon will protect us from ending up being ill native ingesting the organisms that have spoiled the food.


Almond nuts can be sweet or bitter, relying on the form of tree castle come from. The sweet almonds (which us eat) execute not save poisonous chemicals. Bitter almonds from one more tree varieties contain chemicals which are toxic come humans.


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Sweet almonds, such together these, space edible together they carry out not contain toxic chemicals, unequal the wild bitterness almonds.
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Cocoa beans come from cocoa pods. Coco is make from cocoa, but cocoa is really bitter. Numerous sugar is added to chocolate to do it sweet. http://www.flickr.com/photos/michaelsgalpert/3681442211/in/photostream/

soon the link in between the tongue and also chemical substances will become clear.


Properties that acids, bases and also neutral substances


corrosive mountain chemical formula necessary immune device

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execute you prefer sour sweets, such together sour worms? The sour taste comes from fumaric acid. Fumaric acid is a herbal acid through a tart taste, that is often included to foods.
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The juice of lemons is well-off in ascorbic mountain (vitamin C) and also citric acid, which makes it taste sour. every acids taste sour. Does this typical that all acids space safe come taste? absolutely NOT! Next, us will find out which acids have to not be tasted under any type of circumstances.


laboratory acids

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concentrated hydrochloric acid is very corrosive and also dangerous. http://www.flickr.com/photos/maticulous/2552655853/

some acids are an extremely dangerous and also must be taken on carefully. These acids room corrosive. They can reason serious burns on her skin. Scientists always wear protective garments when managing these acids. It would be very dangerous come taste them. This acids are most often found and also used in laboratories and particular industrial processes. We will describe them as laboratory acids.

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This scientist is handling an acid. Can you watch he is wearing protective clothing, gloves and safety glasses? http://www.flickr.com/photos/rdecom/4968163345/

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Look out for this label on bottles which contain corrosive substances, together as solid acids. The following table includes the names and also chemical formulae the the 3 most usual laboratory acids. Also though you have actually not learnt how to compose chemical formulae yet, us have contained them here. Friend should take care of containers through these formulae printed on them through care.


learners will just study chemistry formulae in detail in Gr. 9 Matter and also Materials, however, this is a good opportunity to introduce them to the concept especially so the learners room able to recognise dangerous chemistry substances.


The chemistry formula that a substance tells us which elements it contains.


Name that the acid

Formula the the acid

hydrochloric acid

HCl

nitric acid

HNO3

sulfuric acid

H2SO4

there are many other activities acids that we have actually not listed. These are just the most common ones.


You have actually a laboratory mountain inside her body?! her stomach consists of hydrochloric mountain (HCl). HCl helps malfunction the food because that digestion. Your stomach has actually a really mucous lining i beg your pardon helps safeguard it indigenous the strong acid.


various other acids in the foods items we eat are not dangerous. In fact, some are even critical for our health and well-being. Let"s now have actually a look at mountain that space safe to handle.


Natural and household acids not all acids space dangerous. One such acid is called ascorbic acid, or vitamin C. Vitamin C help our immune system. Which foods contain vitamin C? have a look in ~ the pictures.


Most world associate oranges with a high vitamin C content, but there space other foodstuffs which space much greater in vitamin C. These incorporate chillies, guavas, strawberries, bell peppers, broccoli, kiwi fruits and also papaya.


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Kiwi fruit. http://www.flickr.com/photos/dan4th/5317566258/
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Strawberries.
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Bell peppers.
If you carry out not have enough vitamin C in your diet friend may construct a number of symptoms: friend may become tired easily, bruise easily, build bleeding gums, dried skin and also hair, come to be moody and also lose weight. These are all symptom of a dilute immune system.


we will speak to the acids that we uncover in food natural acids. Plenty of of these herbal acids are found in the kitchen. Hence they are likewise sometimes called household acids.

One very well-known household acid is acetic acid. Vinegar is a mixture the a tiny amount of acetic acid liquified in water. For this reason vinegar is a equipment of acetic mountain in water.

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heart vinegar and balsamic vinegar.

This is a an excellent place to briefly revise several of the principles learnt in Gr. 6 about solutions and also mixtures, and to refer earlier to thing 2 around separating mixtures.

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Formic mountain is what offers ants their sting once they bite. "Formic" originates from the Latin word because that ant "formica".


True or false? INSTRUCTIONS:

Let"s summary revise few of the ideas we have actually learnt therefore far. Listed below are some statements. You have to state even if it is they are true or false. If they room false, define why.

True or false?