Answer:
Volume of the sulfuric acid (25cm³), same mass of each metal (1g)
Explanation:
In an experiment, the CONTROL VARIABLE also known as constant is the variable that is kept unchanged for all groups in an experiment. This is done in order not to influence the outcome of the experiment.
In this case, students are trying to investigate the reactivity of four different metals. They added 1 g of each metal to 25cm³ of sulfuric acid and recorded the temperature change. Based on the explanation of control variable above, the VOLUME OF SULFURIC ACID (25cm³) and the MASS OF EACH METAL (1g) are the CONTROL VARIABLES because they are the same or unchanged in this experiment.
Answer : (b) The rate law expression for the reaction is:
![\text{Rate}=k[SO_2]^2[O_2]](https://tex.z-dn.net/?f=%5Ctext%7BRate%7D%3Dk%5BSO_2%5D%5E2%5BO_2%5D)
Explanation :
Rate law : It is defined as the expression which expresses the rate of the reaction in terms of molar concentration of the reactants with each term raised to the power their stoichiometric coefficient of that reactant in the balanced chemical equation.
The general reaction is:
The general rate law expression for the reaction is:
![\text{Rate}=k[A]^a[B]^b](https://tex.z-dn.net/?f=%5Ctext%7BRate%7D%3Dk%5BA%5D%5Ea%5BB%5D%5Eb)
where,
a = order with respect to A
b = order with respect to B
R = rate law
k = rate constant
![[A]](https://tex.z-dn.net/?f=%5BA%5D)
and ![[B]](https://tex.z-dn.net/?f=%5BB%5D)
= concentration of A and B reactant
Now we have to determine the rate law for the given reaction.
The balanced equations will be:
In this reaction, 
and 
are the reactants.
The rate law expression for the reaction is:
![\text{Rate}=k[SO_2]^2[O_2]^1](https://tex.z-dn.net/?f=%5Ctext%7BRate%7D%3Dk%5BSO_2%5D%5E2%5BO_2%5D%5E1)
or,
Answer:
Because number of electrons becomes greater than protons and atom form anion.
Explanation:
In order to understand this problem we must know about anion and cation.
Anion:
When an atom gain the electrons anion is formed. The negative sign shows that atom gain electron because number of electron are greater than protons or we can say that negative charge becomes greater than positive charge.
Cation:
When atom lose electron cation is formed. The atom thus have positive charge because number of positive charge i.e protons are increased are greater than negative charge or electron.
In given problem N gain three electrons which means negative charge becomes greater that's why the extra electron gained by atoms are written as -3.
