Class 10 Chemistry (India)
- Introduction to pH
- Effect of pH on strength of acids and bases
- Identify the nature of a substance based on pH
- Strong and weak acids/bases
- Strength of solution vs concentration
- pH change & the concentration of H+/OH-
- Effect of concentration on pH change
Introduction to pH
Introduction to pH. Chart from Anatomy & Physiology, Connexions Web site. http://cnx.org/content/col11496/1.6/, Jun 19, 2013. user CC-BY.
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- Sal: If you are going to taste something in order to see if they are basic or acidic, make sure that they are in the middle range of the ph scale
Me: (Sees that there is urine and blood on the scale) Uhhhh yeah, I don't think so.(19 votes)
- it is advised not taste acids and bases but that doesnt mean that you can't taste them....he means that tasting urine and blood wont cause any effect on your body(12 votes)
- Is sugar a basic or acidic pH? What about lemon juice with a tablespoon of sugar in it?(7 votes)
- Sugar has a neutral pH which means it is neither basic or acidic just like water. However, some processed sugars may be a little acidic or basic based on how they were made. Lemon juice with added sugar will be slightly acidic as the lemon would bring down the pH of the mixture.(16 votes)
- What happens when you mix something with a high pH like liquid drain cleaner with something that has a low pH like battery acid?(5 votes)
- If you mix any solution of high ph with a solution of low ph you would get a neutral solution(12 votes)
- On the pH chart in this video, it shows that black coffee is acidic with pH 5. But why does black coffee taste bitter and not sour? Aren't bases supposed to be bitter and acids supposed to be sour?(6 votes)
- Good question! This was a problem that has puzzled scientists for decades, and scientists were only able to identify a few compounds responsible for bitterness in coffee.
Scientists discovered in 2007 that when roasted, a chemical compound present in coffee called chlorogenic acid gets broken down into chlorogenic acid lactones, which further gets broken down into phenylindanes upon further roasting. Both of these compounds are known to be bitter. This may also be the reason why coffee tastes sour when not roasted enough. In reality, coffee is a mixture of multiple compounds, meaning that there may be something bitter that has not yet been discovered.
I hope this helped!(8 votes)
- So I can drink blood because it's neutral?(5 votes)
- Even if it happened to be neutral, it would still not be safe to drink it in large quantities. Not only do you risk infecting yourself with a bloodborne pathogen (such as HIV), but due to blood's high iron content, you will overdose on iron and may even end up with a condition called hemochromatosis, which can be life-threatening.
Did this help?(8 votes)
- The acid inside our stomach has a pH level of 2. It can even dissolve metal.
Lemons have a pH level of 2.
Does this mean that my tongue will be in danger of dissolving when I stick my tongue into lemons?😨(I like the taste of lemons)(3 votes)
- No, and for two reasons:
-Saliva actually protects the mouth against erosion! Studies on dental health and the gastrointestinal tract illustrate that saliva protects the mouth from the acids produced by bacteria and serves to neutralize stomach acid if it ended up in the esophagus. This is probably why your mouth waters if you eat something sour (For reference, saliva has a near-neutral pH).
-You aren't dipping your tongue in a large quantity of lemon juice for a long time on a daily basis. Though acidic substances will eventually lead to tooth erosion, it takes time and multiple or large doses for the acid to have an effect. If you eat a lemon a day, you aren't in danger of tongue erosion--the dose is small and you have saliva. But if you stick your tongue in a gallon of lemon juice for a couple of hours every day, you can expect some damage.
Did this help?(8 votes)
- Wait so since lemons are pH 2, does that mean we can't eat them because alot of ppl eat them(4 votes)
- if pH is 2 it doesn't mean we can't eat it . pH 2 only indicates its acidity. lemon has many benefits to not to say "no" to eat it(4 votes)
- If stomach acid has to maintain a pH level of 1 to 2, how does it not eat the stomach and the rest of your body from the inside out?(2 votes)
- Stomach has a layer of mucus to protect it from the action Of acid(7 votes)
- When milk goes bad and becomes known as "sour" does it have a lower pH? And why is it?(4 votes)
- It develops lactic acid that is produced by the bacteria Lactobascilus casei. This lactic acid is sour and further curdles the milk. @6:09(6 votes)
- This really puzzles me: in the internet, the pH level of bitter gourd juices is 4.24–4.45, but bitter gourds taste bitter. Bases taste bitter. Is a bitter gourd a base or an acid?(2 votes)
- Bitter gourd is actually Neutral or an Alkaline.(3 votes)
- [Instructor] What we're going to do in this video is talk about acidity and in particular, we're gonna talk about the pH scale. Now the first question is what does pH stand for and it turns out that there's some debate why we have this lowercase p here, we know why we have the h, and some people will tell you it stands for power of hydrogen, the capital h for hydrogen. Some people will say it's the potential of hydrogen. Some people will say it's the capacity for hydrogen, you might say capacity doesn't start with a p but if you go into Latin, it can. But what do all of these things mean and why do we care about hydrogen so much? Well, it turns out that hydrogen, and in particular, a hydrogen positive ion, and ion is just a positively charged molecule, that a hydrogen ion can play a major role in how acidic or basic something is. And so the pH scale, you're gonna see it go from zero all the way to 14 with of course, seven in the middle, and something that is towards the left, something that is less than seven is considered acidic, and so if you have a pH near zero that is highly, highly, highly acidic, while something to the right is considered basic and something in the middle is considered neutral. And another term for basic you'll sometimes see is alkaline, and alkaline actually comes from Arabic for alkali which was the word that ancient Arab chemists use for a compound that happens to be very basic by our modern definition. But what does it mean to be acidic and what does it mean to be basic and once again, how does that connect with hydrogen ions? Well, it turns out, and I'm not gonna go in depth in this video, is that things that are acidic tend to have lots of hydrogen ions and while things that are basic tend to react, react with these hydrogen ions. There's other definitions for what it means to be an acid or base and we'll go into depth in chemistry class on that, but this is why it's connected with the term pH. Now what are examples of things that are acidic? Well, you see it on this chart right over here. Here, we're going in the vertical direction. Things in our everyday life that are quite acidic, a lot of fruits are quite acidic, for example, lemons and grapefruits and orange juice are quite acidic. They're at the low end of the scale. And some of the telltale signs for acidity is if you were to drink it or eat it, that it would have this kind of sharp sour taste to it, while if you go to the other end of the spectrum, things that are basic, these would be things like bleaches and ammonia solution and we can even go super basic to liquid drain cleaner, and these are going to have more of a slimy texture to it. In fact, even soap is quite basic. And of the basic things that you could eat, you might have a bitter taste associated with it. But to be clear, I really don't recommend eating or drinking anything that is either highly basic or highly acidic, and the reason is is that things that are at the extreme of the pH scale, so things that are either extremely basic or things that are extremely acidic like battery acid or hydrochloric acid, because they're so reactive, they will damage you. If you pour it in your skin, it will damage you. If you ingest it, it will damage your cells and it can even kill you. So don't try to taste things to see whether they're acid or basic, and if you do, try to make sure that they're closer to this middle range of our pH scale. So I've talked a lot about things that are acidic or basic, but also what's interesting is things that we consider to be neutral. So our blood, for example, is quite neutral, and this is something that doctors might measure because if your pH in your blood gets a little bit too high or a little bit too low, that can cause some serious problems. Sea water is pretty close to being neutral. Milk is not that far off of being neutral. Now with that said, in order to read the pH scale appropriately or appreciate the differences in acidity and basicity, it's important to realize that it is not a linear scale. So for example, something that has a pH of eight is not twice as basic as something that has a pH of four. It turns out, when you go form one level of our pH scale to the other, you are going up in basicity, say going from a pH four to a pH of five, by a factor of 10. And so, comparing something with a pH of four to a pH of eight, that thing with the pH of four would be 10, 100, 1,000, 10,000 times more acidic, or you could say the thing with a pH of eight is 10, 100, 1,000, 10,000 times more basic. So I'll leave you there. Keep a lookout when people talk about pH balance or blood pH, and we're also, as we study more and more biology, we're gonna talk about how pH might influence some biological reactions and especially once you get into chemistry, pH will inform us what type of reaction is likely to happen.