All of the problems in this set are stoichiometry problems with at least one equation participant as a gas at STP. These questions always refer to chemical reaction.So before we calculating,we must write and balance the equation.You will be given an amount of one of the equation to calculate how much another one of the equation.We know:1 mol of gas=22.4 liters at STP.If the question refer to the mass of one of the equation, we must use the formula weight of the material to change from mass to mols.Then we can work out the volume of the gas of that equation.Here is an example.
10 grams of calcium carbonate,CaCO3,was produced when carbon dioxide was added to lime water (calcium hydroxide in solution). What volume of carbon dioxide at STP was needed?
Given:10 grams of CaCO3 (the mass of CaCO3)
Find:the volume of carbon dioxide(in liters at STP)
CO2 + Ca(OH)2 CaCO3 + H2O
Look~we work out the question!
BUT!NOTICE!IT'S At STP only!
Now let's look the map,it's the relationship between mass,moles&volume.
Then you can deal with all this kind of questions,can't you?
Today, we learned how to do stoichiometry calculations involving particles, moles, and mass. These calculations are somewhat similar to mole conversions except, instead of converting between particles, moles, or mass of just one element in the problem, you can convert between particles, moles, or mass of more than one element. *But remember, they are much harder than mole conversioins because you have to use your knowledge of all the mole conversions we've learned in the past, plus what we learned last day about the mole ratio to do these stoichiometry calculations.
Stoichiometry
a branch of chemistry that deals with the quantitative relationships that exist between the reactants and products in chemical reactions. In a balanced chemical reaction, the relations among quantities of reactants and products typically form a ratio of whole numbers. For example, in a reaction that forms ammonia (NH3), exactly one molecule of nitrogen (N2) reacts with three molecules of hydrogen (H2) to produce two molecules of NH3:
N2 + 3H2 → 2NH3
A chemical equation is an expression of a chemical process. For example:
AgNO3(aq) + NaCl(aq) ---> AgCl(s) + NaNO3(aq)
In this equation, AgNO3 is mixed with NaCl. The equation shows that the reactants (AgNO3 and NaCl) react through some process (--->) to form the products (AgCl and NaNO3). Since they undergo a chemical process, they are changed fundamentally.
Often chemical equations are written showing the state that each substance is in. The (s) sign means that the compound is a solid. The (l) sign means the substance is a liquid. The (aq) sign stands for aqueous in water and means the compound is dissolved in water. Finally, the (g) sign means that the compound is a gas.
Coefficients are used in all chemical equations to show the relative amounts of each substance present. This amount can represent either the relative number of molecules, or the relative number of moles (described below). If no coefficient is shown, a one (1) is assumed.
To solve questions as conversions, you need to have conversion factors. Conversion factors relate units to one another. For example, there are 100 cents in 1 dollar, or 100 cents = $1. To use this as a conversion factor, write it as a fraction:
Since 100 cents = 1 dollar, this fraction is equal to 1. That means you can multiply it by anything else, and still have the same quantity that you started with. For example, if you want to convert $5.27 to cents, you can multiply it by the fraction. The dollars cancel out, leaving you with 525 cents:
We can also flip the fraction to get a new conversion factor:
As long as the top and bottom are equal to one another, and we're careful to cancel out units to see what we have left, we can string conversion factors like this together to convert from a starting number to a final answer.
That brings us to stoichiometry. Stoichiometry is the study of relationships in chemical reactions. in other words, it's the study of what amounts of things are equal to amounts of other things in chemical reactions.
CaCO3 + H2O
