Answer:
21.2 g
Explanation:
Step 1: Given data
- Molar concentration of the solution (C): 0.400 mol/L
- Volume of solution (V): 500 mL (0.500 L)
Step 2: Calculate the moles of Na₂CO₃ (solute) in the solution
We will use the definition of molarity.
C = moles of solute / liters of solution
moles of solute = C × liters of solution
moles of solute = 0.400 mol/L × 0.500 L = 0.200 mol
Step 3: Calculate the mass corresponding to 0.200 moles of Na₂CO₃
The molar mass of Na₂CO₃ is 105.99 g/mol.
0.200 mol × 105.99 g/mol = 21.2 g
Answer:
25,050 calories.
Explanation:
A calorie is the amount of energy needed to raise the temperature of one gram of water 1 degree centigrade. If we are raising 835 grams of water 30 degrees then we multiply 835*30 to get 25,050 calories.
Answer:
False
Explanation:
A liquid has a definite shape and takes on the volume of its container. A gas has both the shape and the volume of its container. The particles in a gas cannot be compressed into a smaller volume. Liquids tend to contract when heated.
Hope this helps
Answer:
Mass of NaF in 250 g tube of toothpaste = 100 mg of NaF
Explanation:
Mass of fluoride per gram of toothpaste = 1 mg
From the given data, the fluoride compound that is most often used in toothpaste is sodium fluoride, NaF, which is 45% fluoride by mass, mass of sodium fluoride per gram of toothpaste can be determined as follows:
1 mg of fluoride per gram of toothpaste = 45% total mass of NaF per gram of toothpaste
100% mass of NaF in toothpaste = 100/45 * 1 mg = 2.22 mg of NaF.
Therefore, mass of NaF per gram of toothpaste is 2.22 mg.
The mass of NaF in 250 g of toothpaste is then calculated below:
In 250 g of toothpaste, mass of NaF = 250 * 2.22 mg = 99.9 mg of NaF
