1. two compounds form
2. precipitate forms
3. ions exchanged between the two reactants
Answer:
The time decreases steadily
Explanation:
We know that the rate of chemical reaction is defined as how fast or slow a chemical reaction proceeds. Hence a chemical reaction is said to proceed at a faster rate if it takes a lesser time for the reaction to get to completion.
There are certain factors that affects the rate of reaction, prominent among them is the concentration of reactants. Concentration simply means the amount of substance in a system.
Taking a look at the table given in the question, we will realize that the volume of HCl remained constant, the volume of thiosulphate increased steadily while the volume of water decreased steadily. Remember that concentration increases when less water is added to the system. This implies that the reactant concentration increases steadily. Hence, according to the collision theory, particles collide more frequently and the rate of reaction increases.
As the rate of reaction increases, it now takes a lesser time for the reaction to get to completion (indicated by the disappearance of the cross). Hence as we move down the table, it takes lesser and lesser time for the cross to disappear. This means that the column for time will decrease steadily.
Answer:
2.1x10⁹ years
Explanation:
U-238 is a radioactive substance, which decays in radioactive particles. It means that this substance will lose mass, and will form another compound, the Pb-206.
The time need for a compound loses half of its mass is called half-life, and knowing the initial mass (mi) and the final mass (m) the number of half-lives passed (n) can be found by:
m = mi/2ⁿ
The mass of Pb-206 will be the mass that was lost by U-238, so it will be mi - m. Thus, the mass ration can be expressed as:
(mi-m)/m = 0.337/1
mi - m = 0.337m
mi = 1.337m
Substituing mi in the expression of half-life:
m = 1.337m/2ⁿ
2ⁿ = 1.337m/m
2ⁿ = 1.337
ln(2ⁿ) = ln(1.337)
n*ln(2) = ln(1.337)
n = ln(1.337)/ln2
n = 0.4190
The time passed (t), or the age of the sample, is the half-life time multiplied by n:
t = 4.5x10⁹ * 0.4190
t = 1.88x10⁹ ≅ 2.1x10⁹ years
N(H₂O)=1g÷18g/mol=0,055mol
N(H₂O)=0,055mol · 6·10²³ 1/mol (Avogadro number)= 3,33·10²² molecules.
Electrical energy to light and heat energy
