# Need help with (Acids and Bases) high school exam

• iwantcalculus
In summary, the student is looking for similar questions and problems to the ones they found on the exam. They are looking for help with these problems and want to know what other similar problems might be on the exam.
iwantcalculus
< Mentor Note -- thread moved to HH from the technical PF forums, so no HH Template is shown >

Hello!

So our teacher puts some really hard questions in acids and bases exams, and I would like someone to help me find similar questions and know how to solve these questions..

So the first lessons were about acids and bases, and the lesson talked in general about acids and bases ( properties, arrhenius/bronsted lowry/lewis , acid ionization and base dissociation, naming acids , etc)

But then in the exam he gave us some challenging questions :
write the ionization reaction for the following compound :
al(h2o)6 3+ ( weak acid)

While solving the sample problems all the questions were pretty straightforward acids like HCl + H2O --> H3O+ + CL-

but now i found this weird acid ... [ al(h2o)6 3+ ( weak acid) ]

I searched online to find the answer and found it :

Al (H2O)6 3+ <---double arrows---> Al(OH)(H2O)5 2+ and H+
problem is, we usually solve with H3O+ not with H+... ( I know they're the same thing but I'm totally unfamiliar with the H+ thing...)

can someone help with this question? how did we find the answer? and what are similar questions that can come like this ( hard acid/base ionization/dissociation problems like this)...
Second challenging question :

Geologist drops HCl on a rock , gas bubbles form. What might he conclude about the gas and rock ?

gas: carbon dioxide rock : contains carbonate mineral?

I didn't know these correct answers on the exam, but what are some similar problems to this one that can occur in the exam?

and how can I study for the "harder" problems since the book's examples are too straightforward?

Last edited by a moderator:
iwantcalculus said:
Al (H2O)6 3+ <---double arrows---> Al(OH)(H2O)5 2+ and H+

If you don't like the H+ alone just add water on the LHS, and you will get H3O+ on the right. After all, reaction takes place in water, so there is plenty of water molecules around.

When it comes to the second question - how carbonates react with strong acids is just one of the things you have to remember.

Sorry, can't help you with finding other problems, perhaps someone else will be able to chime in. Where do you live? I can offer you some insight about Polish books, but I doubt they will help you much ;)

For your second question I think if you have to ask, then frankly your teaching is short-changing you, because if you had had a live demonstration you would never forget it. I hope it improves for you later. Chemistry just cannot be learned or appreciated from book and questionnaire alone. Pending improvement of the teaching, you should supplement it by looking online for demonstrations, like those cited below. Do this for all reactions you can. This is not as good as seeing directly or hands-on, but in compensation the sources are many and you can see them as many times as you want.

Calcium Carbonate and Hydrochloric Acid Demo - YouTube

Reaction of Calcium Carbonate with Hydrochloric Acid - YouTube

Experiment 4.1 Investigating action of heat, water and acids on calcium carbonate

I started to write about chemistry teaching in general, but it got too long and a bit of a rant, so maybe in another thread some other time soon.

Edit by Borek: corrected videos for you :)
Thx borek, ep

Last edited:

## 1. What are acids and bases?

Acids and bases are two types of chemical compounds that have distinct properties and characteristics. Acids are substances that have a pH value of less than 7 and are able to donate hydrogen ions in a solution. Bases, on the other hand, have a pH value of more than 7 and are able to accept hydrogen ions. They are commonly found in many household products and are important in various chemical processes.

## 2. What is the pH scale?

The pH scale is a numerical scale ranging from 0 to 14 that measures the acidity or basicity of a solution. A pH of 7 is considered neutral, while values below 7 are acidic and values above 7 are basic. The scale is logarithmic, meaning that each increase or decrease in pH value represents a tenfold change in acidity or basicity.

## 3. How do you determine the pH of a solution?

The pH of a solution can be determined using a pH meter or pH paper. A pH meter measures the electrical potential difference between a reference electrode and a sensing electrode, while pH paper turns a specific color based on the pH level of the solution. Both methods provide a numerical value that corresponds to the pH scale.

## 4. What are some common properties of acids and bases?

Acids and bases have several common properties. Acids tend to be sour in taste, corrosive, and can react with metals to produce hydrogen gas. Bases, on the other hand, have a bitter taste, are slippery to the touch, and can neutralize acids. Both acids and bases can also conduct electricity when in solution.

## 5. How are acids and bases used in everyday life?

Acids and bases have many practical uses in everyday life. Acids are commonly used in cleaning products, such as vinegar and lemon juice, to dissolve dirt and grime. Bases, such as ammonia and baking soda, are used in household cleaners and also in baking. They are also important in industrial processes, such as in the production of fertilizers, plastics, and pharmaceuticals.

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