Answer:
4.97 X 10^13 ATOMS OF Zn
Explanation:
how many atoms of zinc are required to weigh 5.4 ng
a nano gram is 10^-9 grams
Zinc has an atomic mass of 65.39 gm/moles
there is an Avogadros number of atoms in a mole
65.39 GRAMS PER MOLE
65.39 g/(6.022 X 10^23)how many atoms of zinc are required to weigh 5.4 ng
GRAMS PER ATOM
1.086 GRAMS PER 1O^22 ATOMS
1 atom of Zn weighs 1.086 X 10^9 X 1O^-22 n grm=
1,086 X 10^-13 n gm
Y tines 1.086 X 10^-13 = 5.4 n gm
Y = 5.4/ (1.086 X 10^-13) =
4.97 X 10^13 ATOMS OF Zn
CHECK
(4.97 X 10^13 ) X 65.39 gm/(6.022 X 10^23) =
5.397 X 10^-9 =
5.4 n g
Answer:
-586.56 kJ/mol is the standard enthalpy of the 3rd reaction.
Explanation:
...[1]
...[2]
..[3]
The unknown standard enthalpy of third reaction can be calculated by using Hess's law:
The law states that 'the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps'.
[2] - 2 × [1] = [3]
![O_2+4HI\rightarrow 2H_2O(g)+2I_2(s)](https://tex.z-dn.net/?f=O_2%2B4HI%5Crightarrow%202H_2O%28g%29%2B2I_2%28s%29)
![\Delta H^{o}_{3}=\Delta H^{o}_{2}-2\times \Delta H^{o}_{1}](https://tex.z-dn.net/?f=%5CDelta%20H%5E%7Bo%7D_%7B3%7D%3D%5CDelta%20H%5E%7Bo%7D_%7B2%7D-2%5Ctimes%20%5CDelta%20H%5E%7Bo%7D_%7B1%7D)
![=-483.64 kJ/mol - 2\times (52.96 kJ/mol)=-586.56 kJ/mol](https://tex.z-dn.net/?f=%3D-483.64%20kJ%2Fmol%20-%202%5Ctimes%20%2852.96%20kJ%2Fmol%29%3D-586.56%20kJ%2Fmol)
The standard enthalpy of the 3rd reaction is -586.56 kJ/mol.The negative sign indicates that energy is released during this reaction.
The two key characteristics of a good scientific investigation is observation and hypothesis.
Answer: The above equation is balanced.
Explanation: Each individual atom are balanced. For Mg it has 1 atom in the reactant and product side. 2 atoms for H and 2 for Cl in both sides.