Answer:
0.79 g
Explanation:
Let's introduce a strategy needed to solve any similar problem like this:
- Apply the mass conservation law (assuming that this reaction goes 100 % to completion): the total mass of the reactants should be equal to the total mass of the products.
Based on the mass conservation law, we need to identify the reactants first. Our only reactant is sodium bicarbonate, so the total mass of the reactants is:
We have two products formed, sodium carbonate and carbonic acid. This implies that the total mass of the products is:
Apply the law of mass conservation:
Substitute the given variables:
Rearrange for the mass of carbonic acid:
Answer:
t = 7.58 * 10¹⁹ seconds
Explanation:
First order rate constant is given as,
k = (2.303
/t) log [A₀]
/[Aₙ]
where [A₀] is the initial concentraion of the reactant; [Aₙ] is the concentration of the reactant at time, <em>t</em>
[A₀] = 615 calories;
[Aₙ] = 615 - 480 = 135 calories
k = 2.00 * 10⁻²⁰ sec⁻¹
substituting the values in the equation of the rate constant;
2.00 * 10⁻²⁰ sec⁻¹ = (2.303/t) log (615/135)
(2.00 * 10⁻²⁰ sec⁻¹) / log (615/135) = (2.303/t)
t = 2.303 / 3.037 * 10⁻²⁰
t = 7.58 * 10¹⁹ seconds
Answer:
I beleive the first option is correct
Answer:
23.2 mols
Explanation:
(23.2 mol H2)(2 mol H2O) /(2 mol H2) = 23.2 mol H2O
you have to do stoichiometry - so start of with what you are given, which is 23.2 mols of hydrogen, then to cancel out mols of hydrogen, divide by what is in the equation: so 23.2 mols H2 / 2 mols H2. Next, to get mols of H2O multiply that number by the mols of water in the equation.
this answer makes sense because as you can see in the equation, there are 2 H2:2 H2O, so the amounts should be the same.
hope this helps! make sure to practice because it is ESSENTIAL that you understand this, especially if you plan on taking ap chem. good luck! :)
