Answer:
Sodium (Na) has atomic number 11.
Answer:
The 197Au isotope has 79 protons, 79 electrons and 118 neutrons
Explanation:
Step 1: The isotope = 197Au
Step 2: Calculate neutrons, electrons and protons
197 = Number of protons + number of neutrons
Isotopes always have the same proton number ( is the same as the atomic number). For Gold (Au) is this 79.
The number of electrons is equal to the number of protons in a neutral atom. Since we have 79 protons, there are also 79 electrons.
All isotopes of Au have a different number of neutrons.
The number of neutrons = 197 -79 = 118 neutrons
The 197Au isotope has 79 protons, 79 electrons and 118 neutrons
Answer:
C₂ = 1.26 mol/dm³
Explanation:
Given data:
Volume of HCl =V₁ = 15.7 cm³
Volume of LiOH = V₂ = 25 cm³
Concentration of HCl =C₁ = 2 mol/dm³
Concentration of LiOH =C₂= ?
Solution:
Chemical equation:
LiOH + HCl → LiCl + H₂O
Formula:
C₁V₁ = C₂V₂
by putting values,
15.7 cm₃× 2 mol/dm³ = C₂× 25 cm³
C₂ = 15.7 cm₃× 2 mol/dm³ / 25 cm³
C₂ = 31.4 cm₃.mol/dm³ / 25 cm³
C₂ = 1.26 mol/dm³
<span>0.0687 m
The balanced equation is
BaCl2 + Na2SO4 ==> BaSO4 + 2 NaCl
Looking at the equation, it indicates that there's a 1 to 1 ratio of BaCl2 and Na2SO4 in the reaction. So the number of moles of each will be equal. Now calculate the number of moles of Na2SO4 we had. Start by looking up atomic weights.
Atomic weight sodium = 22.989769
Atomic weight sulfur = 32.065
Atomic weight oxygen = 15.999
Molar mass Na2SO4 = 2 * 22.989769 + 32.065 + 4 * 15.999 = 142.040538 g/mol
Moles Na2SO4 = 0.554 g / 142.040538 g/mol = 0.003900295 mol
Molarity is defined as moles per liter, so let's do the division.
0.003900295 mol / 0.0568 l = 0.068667165 mol/l = 0.068667165 m
Rounding to 3 significant figures gives 0.0687 m</span>
