Answer is: elements in the same group have similar chemical properties.
Periodic law<span> is the arrangement of the </span>elements<span> in order of increasing atomic number.
</span>For example all alkaline metals (I group of periodic table, Na, K, Cs...) loose one electron in chemical reaction and react vigorously with water.
Answer: 19.8 l
Explanation:
1) Chemical equation:
2Ca + O₂ → 2CaO
2) Mole ratios: 2 mol Ca : 1 mol O₂ : 2 mol CaO
3) Convert 35.4 g of Ca to moles:
n = mass in grams / molar mass = 35.4 g / 40.1 g/mol = 0.883 mol
4) Volume proportion: 1 mol of gas at STP = 22.4 l
1 mol at STP 0.883 mol at STP
--------------------- = ------------------------------
22.4 l x
⇒ x = 0.883 mol × 22.4 l / 1 mol = 19.8 l ← answer
Answer:
13.20
Explanation:
Step 1: Calculate the moles of Ba(OH)₂
The molar mass of Ba(OH)₂ is 171.34 g/mol.
0.797 g × 1 mol/171.34 g = 4.65 × 10⁻³ mol
Step 2: Calculate the molar concentration of Ba(OH)₂
Molarity is equal to the moles of solute divided by the liters of solution.
[Ba(OH)₂] = 4.65 × 10⁻³ mol/60 × 10⁻³ L = 0.078 M
Step 3: Calculate [OH⁻]
Ba(OH)₂ is a strong base according to the following equation.
Ba(OH)₂ ⇒ Ba²⁺ + 2 OH⁻
The concentration of OH⁻ is 2/1 × 0.078 M = 0.16 M
Step 4: Calculate the pOH
pOH = -log OH⁻ = -log 0.16 = 0.80
Step 5: Calculate the pH
We will use the following expression.
pH + pOH = 14
pH = 14 - 0.80 = 13.20
Hey there:
1 cm³ = 1 mL
D = m / V
7.25 = 12.9 / V
V = 12.9 / 7.25
V = 1.779 cm³
Answer: Option C) 9.5
Explanation:
Given that,
pOH of solution = ?
pH of solution = 4.5 (it is an acidic solution because any pH values less than 7.0 is said to be acidic)
Recall that pH is the negative logarithm of hydrogen ion concentration in the solution while pOH is the negative logarithm of hydroxide ion concentration in the solution.
Hence, pH + pOH = 14
4.5 + pOH = 14
pOH = 14 - 4.5
pOH = 9.5
Thus, the pOH of the same solution is 9.5
