That really depends on the age of the periodic table you’re referring to. Mendeleev’s original periodic table had only 50 elements. Today, the most modern Periodic table has 118 elements.
To determine the mass of the iceberg, we simply multiply the density with the volume. Density is a value for mass, such as kg, divided by a value for volume, such as m3. Density is a physical property of a substance that represents the mass of that substance per unit volume. Remember that the units should be homogeneous. We calculate as follows:
mass = density x volume
mass = 0.92 g /cm^3 ( 9470 ft^3) ( 30.48 cm / 1 ft )^3 ( 1 kg / 1000 g ) = 265.55 kg
Answer : The enthalpy change of reaction is -1800 kJ
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The given final reaction is,
The intermediate balanced chemical reaction will be,
(1) 
(2) 
First we will multiply reaction 1 by 2 and reverse reaction of reaction 2 by 3 then adding both the equation, we get :
The expression for final enthalpy is,
![\Delta H=[n\times \Delta H_1]+[n\times (-\Delta H_2)]](https://tex.z-dn.net/?f=%5CDelta%20H%3D%5Bn%5Ctimes%20%5CDelta%20H_1%5D%2B%5Bn%5Ctimes%20%28-%5CDelta%20H_2%29%5D)
where,
n = number of moles
![\Delta H=[2mole\times (-1680kJ/mole)]+[3\times -(-520kJ/mole)]](https://tex.z-dn.net/?f=%5CDelta%20H%3D%5B2mole%5Ctimes%20%28-1680kJ%2Fmole%29%5D%2B%5B3%5Ctimes%20-%28-520kJ%2Fmole%29%5D)
Therefore, the enthalpy change of reaction is -1800 kJ
Answer:
The answer to your question is the second option
Explanation:
Reaction
Al₂(SO₄)₃ + KOH ⇒ Al(OH)₃ + K₂SO₄
Process
1.- Check if the reaction is already balanced
Reactants Elements Products
2 Aluminum 1
3 Sulfur 1
13 Oxygen 7
1 Potassium 2
1 Hydrogen 3
The reaction is unbalanced
2.- Balance the reaction
1Al₂(SO₄)₃ + 6KOH ⇒ 2Al(OH)₃ + 3K₂SO₄
Reactants Elements Products
2 Aluminum 2
3 Sulfur 3
18 Oxygen 18
6 Potassium 6
6 Hydrogen 6
Now the reaction is balanced. The coefficients are 1, 6, 2, 3.
Answer:
6.475 M
Explanation:
Number of moles = 25.9 moles
Volume = 4.00 L
Molarity = ?
The relationship between the quantities is given as;
Molarity = Number of moles / Volume
Molarity = 25.9 / 4
Molarity = 6.475 M
