Answer is: Zn + Cu2+ → Zn2+ + Cu.
In this chemical reaction, there is transfer of electrons from zinc (Zn) to copper (Cu). Zinc change oxidation number from 0 to +2 (lost electrons) and copper change oxidation number from +2 to 0 (gain electrons).
Oxidation half reaction: Zn⁰ → Zn²⁺ + 2e⁻.
Reduction half reaction: Cu²⁺ + 2e⁻ → Cu⁰.
In other chemical reactions, there is no change of oxidation number of elements.
The reaction between NaOH and HCl is as follows
NaOH + HCl ---> NaCl + H₂O
for neutralisation, H⁺ ions react with an equivalent amount of OH⁻ ions.
Number of NaOH moles reacted = 0.270 M/1000 mL/L x 37 mL = 0.00999 mol
number of HCl moles reacted = 0.270 M/1000 mL x 27 mL = 0.00729 mol
HCl reacts with NaOH in 1:1 molar ratio
Number of excess NaOH moles remaining - 0.00999 - 0.00729 = 0.0027 mol
total volume of solution = 37 mL + 27 mL = 64 mL = 0.064 L
Since there's excess OH⁻ ions, we can calculate pOH value first
pOH = - log [OH⁻]
[OH⁻] = 0.0027 mol / 0.064 L = 0.042 mol/L
pOH = -log(0.042 M)
pOH = 1.37
by knowing pOH we can calculate pH using the following equation;
pH + pOH = 14
pH = 14 - 1.37
pH = 12.63
Answer: The definition of an endothermic reaction is that the products have higher energy than the reactants, resulting in a positive enthalpy of reaction.
Explanation:
<span>6.2×6.022×<span>1023</span>=3.733×<span>1024</span></span><span> atoms.</span>
