How to Calculate a Milliequivalent | Sciencing
You do not have the same numbers of sulfur, antimony, or fluorine atoms on each side of the equation. You cannot say anything about. According to Wikipedia: > The equivalent weight of an element is the gram atomic weight What is the difference between millimole and milliequivalent?. A milliequivalent is a chemistry term related to the mass and concentration in solution of different solutes.
I just needed some negatively charged monovalent, and chloride suits our purposes. And we know, just as before, we need a whole mole of them.
- Equivalent (chemistry)
- Equivalent weight
And so if that's the case, how many calciums will bind to a chloride, and vice versa. How many chlorides will bind to a calcium? So let's imagine we have a little chloride and calcium party, and they can meet each other.How To Calculate Normality & Equivalent Weight For Acid Base Reactions In Chemistry
Well, what's going to happen is, that you're going to have a calcium there, and a chloride there, and a chloride there, right? Because this will come here. This will come here. And they're going to basically bind and make this. They're going to make CaCl2, because the chlorides are only one negative charge-- actually, and this is two positive charges.
I'm flipping around my negatives and positives.
Negative, negative, and plus 2. So you know that for every one calcium, you're going to get two chlorides. So let me write that out very clearly. So for every one calcium-- or actually I can write for every two chlorides you get one calcium, right?
Equivalent (chemistry) - Wikipedia
But at least the math works out there. So far so good. And I said that we could flip around the equation, and we can. We could say, well, then 1 mole-- now all I did is multiplied both sides by 1 mole of calcium-- I'm not writing clearly right now, sorry-- 1 mole of calcium equals 2 equivalents.
So there is how people usually phrase it. They'll say, OK, well, how many equivalents do you get for 1 mole of something? And so here you would say the answer is 2. And so I just want to point out something to you, which is that we kind of did this a long way, but here is a quick and dirty way. You could say, well, I know that calcium is divalent, and we know that potassium is monovalent, and here is kind of an interesting pattern that's emerging, right? As this Ca plus 2 emerged, we got 2 equivalents out of it.
Let's test this with a third one. Let's just see what we get if we use, let's say, nitrogen. So let's do nitrogen. Nitrogen is negative 3.
What is an equivalent?
And I have to create my boundary, and on the other side, I need some oppositely charged monovalent. So there's a monovalent and it's opposite-- here's monovalent, check, and it's oppositely charged, check. Opposite of the negative, right? It meets our requirements. And I need a mole of them. So I have to draw out a mole, and you know there's no way I can do that, as I said before.
And so just imagine 1 mole of these guys. And the question, again, is how much nitrogen do I need to balance all this out?
And I'm gonna just underline in red the clue. So here's the clue. And let's now actually go through the steps of figuring it out kind of the longer way. So let's imagine you have a nitrogen here, negative 3, and it's going to be at this, let's say, cocktail party, and it meets some protons.
And in this case, 3 of them come by. So it's going to form NH3, right?
And I'm going to flip this around, just as we did before. I could say, then let me change that-- I could say, then 1 mole of nitrogen equals 3 equivalents. And remember, we underlined that little 3 in the beginning, and I'm going to underline it again. And now you can very clearly see the pattern that's emerging. So you can see that any time you look at the cation or anion that you're talking about, if you look at the number-- like if it's, let's say, magnesium, that's 2 plus, or calcium is 2 plus-- then you can know immediately that that probably means, if you did the work the long way like we just did, that the equivalents are going to work out to the same number.
So nitrogen has 3 equivalents.
Magnesium or calcium have 2 equivalents. With experiment as a guide, you find Wenzel's equivalents, Mitscherlich's equivalents, they are nothing else but molecular groups. If I had the power, I would erase the word 'atom' from science, persuaded that it oversteps the evidence of experiment; and, in chemistry, we must never overstep the evidence of experiment.
What is an equivalent? (video) | Khan Academy
For a start, the scale based on hydrogen was not particularly practical, as most elements do not react directly with hydrogen to form simple compounds.
This system can be extended further through different acids and bases. Copper will react with oxygen to form either brick red cuprous oxide copper I oxidewith Supporters of atomic weights could turn to the Dulong—Petit lawwhich relates the atomic weight of a solid element to its specific heat capacityto arrive at a unique and unambiguous set of atomic weights.
However, these nineteenth-century "equivalents" were not equivalents in the original or modern sense of the term. Since they represented dimensionless numbers that for any given element were unique and unchanging, they were in fact simply an alternative set of atomic weights, in which the elements of even valence have atomic weights one-half of the modern values.
This fact was not recognized until much later. However, equivalent weights continued to be used for many compounds for another hundred years, particularly in analytical chemistry.
Equivalent weights of common reagents could be tabulated, simplifying analytical calculations in the days before the widespread availability of electronic calculators: Use in general chemistry[ edit ] The use of equivalent weights in general chemistry has largely been superseded by the use of molar masses. Equivalent weights may be calculated from molar masses if the chemistry of the substance is well known: Historically, the equivalent weights of the elements were often determined by studying their reactions with oxygen.
Use in volumetric analysis[ edit ] Burette over a conical flask with phenolphthalein indicator used for acid-base titration. When choosing primary standards in analytical chemistrycompounds with higher equivalent weights are generally more desirable because weighing errors are reduced. An example is the volumetric standardisation of a solution of sodium hydroxide which has been prepared to approximately 0.
The equivalent weights of the three acids For sake of example, it shall be assumed that