Mole-mole calculations are not the only type of calculations that can be performed using balanced chemical equations. Recall that the molar mass can be determined from a chemical formula and used as a conversion factor. We can add that conversion factor as another step in a calculation to make a mole-mass calculation, where we start with a given number of moles of a substance and calculate the mass of another substance involved in the chemical equation, or vice versa.
For example, suppose we have the balanced chemical equation
2 Al + 3 Cl 2 → 2 Alcoa
Suppose we know we have 123.2 g of Cl 2. How can we determine how many moles of Alcoa we will get when the reaction is complete? First and foremost, chemical equations are not balanced in terms of grams; they are balanced in terms of moles. So to use the balanced chemical equation to relate an amount of Cl 2 to an amount of Alcoa, we need to convert the given amount of Cl 2 into moles. We know how to do this by simply using the molar mass of Cl 2 as a conversion factor. The molar mass of Cl 2 (which we get from the atomic mass of Cl from the periodic table) is 70.90 g/mil. We must invert this fraction so that the units cancel properly:
Answer:
2.5 mL
Explanation:
Step 1: Given data
- Concentration of the active ingredient (C): 5% v/v
- Volume of the medicine (V): 50 mL
Step 2: Calculate the amount of the active ingredient in the medicine
The concentration of the active ingredient is 5% v/v, that is, there are 5 mL of the active ingredient per 100 mL of the medicine. The volume of the active ingredient is 50 mL of the medicine is:
50 mL Med × 5 mL AI/100 mL Med = 2.5 mL AI
For an arrangement of electrons to be nonpolar in a molecule they need to have equal electron charges.
Answer:
12.5 g
Explanation:
If element R's half life is 2 minutes then we need to divide 100 g by 1/2 3 times. 100/2 = 50/2= 25/2= 12.5 g.
Hope this helps!
