Answer:
The molarity of this KOH solutions 3.21 mol / L (option C is correct)
Explanation:
Step 1: Data given
Mass of KOH = 45.0 grams
Molar mass of KOH = 56.1 g/mol
Volume = 250.0 mL = 0.250 L
Step 2: Calculate moles KOH
Moles KOH = mass KOH / molar mass KOH
Moles KOH = 45.0 grams / 56.1 g/mol
Moles KOH = 0.802 moles
Step 3: Calculate molarity
Molarity KOH solution = moles KOH / volume water
Molarity KOH solution = 0.802 moles / 0.250 L
Molarity KOH solution = 3.21 mol / L
The molarity of this KOH solutions 3.21 mol / L (option C is correct)
1. Potential of a chemical substances to undergo transformation in a chemical reaction is known as chemical energy. The chemical energy is stored in the bonds of chemical compounds.
Hence, in a compound, chemical energy is contained in bonds.
2. The process in which one or more substance known as reactants are converted to one or more completely new substances known as products are formed is known as a chemical reaction.
Hence, during a chemical reaction bonds of the reactants are broken, and bonds of the products are formed.
Answer:
A) positive; added
Explanation:
Based on the reaction:
2NaHCO3(s) + 129kJ → Na2CO3(s) + H2(g) + CO2(g)
<em>2 moles of NaHCO3 requires 129kJ to produce 1 mole of Na2CO3, 1 mole of H2 and 1 mole of CO2.</em>
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That means, the energy must be added being, thus, an exothermic reaction. The exothermic reactions have ΔH >0.
Thus, right answer is:
A) positive; added
You can look at the number of valence electrons and look at the size of the molecule itself to determine which element in this certain group is shown on the model.