Answer:
Approximately 75%.
Explanation:
Look up the relative atomic mass of Ca on a modern periodic table:
There are one mole of Ca atoms in each mole of CaCO₃ formula unit.
- The mass of one mole of CaCO₃ is the same as the molar mass of this compound:
. - The mass of one mole of Ca atoms is (numerically) the same as the relative atomic mass of this element:
.
Calculate the mass ratio of Ca in a pure sample of CaCO₃:
.
Let the mass of the sample be 100 g. This sample of CaCO₃ contains 30% Ca by mass. In that 100 grams of this sample, there would be
of Ca atoms. Assuming that the impurity does not contain any Ca. In other words, all these Ca atoms belong to CaCO₃. Apply the ratio
:
.
In other words, by these assumptions, 100 grams of this sample would contain 75 grams of CaCO₃. The percentage mass of CaCO₃ in this sample would thus be equal to:
.
Answer:
1 atm
Explanation:
Step 1: Write the balanced equation
NH₄OH(aq) ⇒ H₂O(l) + NH₃(g)
Step 2: Calculate the moles corresponding to 8 g of NH₄OH
The molar mass of NH₄OH is 35.04 g/mol.
8 g × 1 mol/35.04 g = 0.2 mol
Step 3: Calculate the moles of NH₃ formed from 0.2 moles of NH₄OH
The molar ratio of NH₄OH to NH₃ is 1:1. The moles of NH₃ formed are 1/1 × 0.2 mol = 0.2 mol
Step 4: Calculate the pressure of 0.2 moles of NH₃ in a container of 5.00 L at 25 °C (298 K)
We will use the ideal gas equation.
P × V = n × R × T
P = n × R × T / V
P = 0.2 mol × 0.0821 atm.L/mol.K × 298 K / 5.00 L
P = 1 atm
Answer:
0.96g of sodium hydride
Explanation:
Equation of reaction:
NaH + H20 = NaOH + H2
Mass of hydrogen gas produced (m) = PVM/RT
P = 765torr - 28torr = 737torr = 737/760 = 0.97atm, V = 982mL = 982cm^3, M = 2g/mol, R = 82.057cm^3.atm/gmol.K, T = 28°C = 28 + 273K = 301K
m = (0.97×982×2)/(82.057×301) = 0.08g of hydrogen gas
From the equation of reaction
1 mole (24g) of sodium hydride produced 1 mole (2g) of hydrogen gas
0.08g of hydrogen gas would be produced by (24×0.08)/2 = 0.96g of sodium hydride
The answer to your question would be: true
Answer:
The moon jelly population increased there were either more births or fewer deaths in the population than before. ... If there are more energy storage molecules available to the moon jellies, they can reproduce more, resulting in more births. Fewer deaths would also cause the jelly population to increase.
Explanation: