I have no idea how to work this problem can anyone help explain this to me?
2H2O=2H2+O2
if 30mL of hydrogen are produced in the reaction above, how many militers of oxygen are produced?
Look at the equation. That's what they are for. The coefficients in the equation tell you that you have 2 mols hydrogen for every 1 mol oxygen. So 2 and 1, 4 and 2, 6 and 3, 8 and 4, 10 and 5 etc. Get the idea?
Do I have to change the milliters into liters? That is where I get confused.
Not unless you want to do so. Here is the way the units work.
30 mL H2 x (1 mol O2/2 mols H2) = ?? mL O2. Notice that you start with 30 mL H2 in the numerator. H2 in the numerator cancels with H2 in the denominator of the second term. mols cancel top and bottom. That leaves mL O2 for the answer and that's what the problem asked for. You COULD change to liters, the answer will come out in liters, then changre back to mL but that's a lot of extra work; especially when the problem asks for mL.
thank you, DrBob, now I understand.
To solve this problem, you need to first understand the balanced chemical equation and use stoichiometry. Let's break it down step by step:
Step 1: Understand the balanced chemical equation
The balanced chemical equation shows the relationship between the reactants and products in a chemical reaction. In this case, we have:
2H2O → 2H2 + O2
This means that 2 molecules of water (H2O) react to produce 2 molecules of hydrogen gas (H2) and 1 molecule of oxygen gas (O2).
Step 2: Use stoichiometry
Stoichiometry is a method used to relate the quantities of reactants and products in a chemical reaction. It allows us to convert between different substances using their respective coefficients in the balanced equation.
In this case, we want to find out how many milliliters of oxygen gas (O2) are produced when 30 mL of hydrogen gas (H2) is produced.
To do this, we'll set up a stoichiometric ratio using the coefficients from the balanced equation.
Step 3: Set up the stoichiometric ratio
From the balanced equation, we know that:
2 molecules of water (H2O) produce 1 molecule of oxygen gas (O2)
This means, the stoichiometric ratio of water to oxygen gas is:
2 mol H2O : 1 mol O2
However, we need to convert this ratio to milliliters (mL) since the volumes are given in mL in the question.
Step 4: Convert to milliliters
To convert the stoichiometric ratio to milliliters, we need to use the densities of hydrogen gas (H2) and oxygen gas (O2).
Density of H2 gas = 0.0899 g/mL
Density of O2 gas = 1.429 g/mL
Given that 2 moles of H2 is produced, we can calculate the mass of H2:
Mass of H2 = 2 moles H2 * molar mass of H2
The molar mass of H2 is approximately 2 g/mol.
Using the density of H2 gas, we can convert the mass of H2 to volume:
Volume of H2 = Mass of H2 / Density of H2 gas
Now, since we know that 30 mL of H2 gas is produced, we can set up a ratio to determine the volume of O2 gas produced.
Step 5: Calculate the volume of oxygen gas
Using the stoichiometric ratio between H2 and O2, we have:
2 mol H2O : 1 mol O2
Since 30 mL of H2 gas is produced, we can set up the equation:
2 mol H2O : 1 mol O2 = 30 mL H2 : x mL O2
Now, we can solve for x (the volume of O2 gas) using cross-multiplication:
2 mol H2O * x mL O2 = 1 mol O2 * 30 mL H2
x = (1 mol O2 * 30 mL H2) / 2 mol H2O
Calculating the value of x gives us the volume of oxygen gas produced in milliliters.
Remember to always double-check your calculations and units to ensure accuracy.