Answer: Change in chemical composition of reactants is an event which must always occur for a chemical reaction to take place.
Explanation:
A chemical reaction is defined as a reaction in which there will always occur change in chemical composition of reactant species.
For example,
Here, chemical composition of both
and HCl changes which leads to the formation of silver chloride and nitric acid. Hence, it is a chemical reaction.
Therefore, we can conclude that change in chemical composition of reactants is an event which must always occur for a chemical reaction to take place.
Answer:
a. HCl + NH₃ ⇄ NH₄Cl
b. KOH + NH₄⁺ ⇄ K⁺ + NH₃ + H₂O
Explanation:
A buffer system is made by a weak base (ammonia, NH₃) and its conjugate acid (ammonium ion NH₄⁺ coming from ammonium chloride NH₄Cl). Its function is to resist abrupt changes in the pH when acids or bases are added.
a. When aqueous hydrochloric acid is added, it reacts with the base of the buffer. The corresponding equation is:
HCl + NH₃ ⇄ NH₄Cl
b. When aqueous potassium hydroxide is added, it reacts with the acid of the buffer. The corresponding equation is:
KOH + NH₄⁺ ⇄ K⁺ + NH₃ + H₂O
Answer: 15.2 grams
Explanation:
Molarity of a solution is defined as the number of moles of solute dissolved per Liter of the solution.
![Molarity=\frac{n\times 1000}{V_s}](https://tex.z-dn.net/?f=Molarity%3D%5Cfrac%7Bn%5Ctimes%201000%7D%7BV_s%7D)
where,
n= moles of solute
= volume of solution in ml
moles of solute (nickel (II) chloride hexahydrate ) =![\farc{\text{given mass}}{\text {Molar mass}}=\frac{xg}{237.69g/mol}](https://tex.z-dn.net/?f=%5Cfarc%7B%5Ctext%7Bgiven%20mass%7D%7D%7B%5Ctext%20%7BMolar%20mass%7D%7D%3D%5Cfrac%7Bxg%7D%7B237.69g%2Fmol%7D)
Putting the values , we get
![0.255= \frac{x\times 1000}{237.69\times 250}](https://tex.z-dn.net/?f=0.255%3D%20%5Cfrac%7Bx%5Ctimes%201000%7D%7B237.69%5Ctimes%20250%7D)
![x=15.2g](https://tex.z-dn.net/?f=x%3D15.2g)
Thus 15.2 grams of nickel (II) chloride hexahydrate are required to prepare 250. mL of aqueous solution whose concentration is 0.255 M.
In a precipitation reaction, one of the product formed is an insoluble precipitate.
The given reactions can be written with phases included as:
A.
: In this reaction one of the product, FeS is insoluble. Therefore, this is a precipitation reaction.
B.
: In this reaction, the product
is a solid(insoluble). So, this is a precipitation reaction too.
C.
: In this reaction, both the products are soluble. So this is not a precipitation reaction.
D.
: In this reaction, both the products are soluble. So this is not a precipitation reaction.
E.
: In this reaction, the product AgCl is a precipitate. So, it is a precipitation reaction.
Answer:
calm, sunny weather; but also cool