Answer:
1. Density can be used to identify a substance
2. Density can be used to ascertain whether a substance will float in water.
Explanation:
The calculation of the density of a substance can be used to identify the substance. If the density of a substance is calculated accurately, and compared with a table of standard densities, then we can identify that substance.
Also, density determines whether an object will float or sink in water. If an object is less dense than water then it will float in water. If it is denser than water, then it will sink in water.
Answer:
0.01 moles of SrCO₃
Explanation:
In this excersise we need to propose the reaction:
K₂CO₃ + Sr(NO₃)₂ → 2KNO₃ + SrCO₃
As we only have data about the potassium carbonate we assume the strontium nitrite as the excess reactant.
1 mol of K₂CO₃ react to 1 mol of Sr(NO₃)₂ in order to produce 2 moles of potassium nitrite and 1 mol of strontium carbonate.
Ratio is 1:1. In conclussion,
0.01 mol of K₂CO₃ must produce 0.01 moles of SrCO₃
4HCl + O₂ → 2Cl₂ + 2H₂O
mole ratio of HCl : O₂ is 4 : 1
∴ if moles of HCl = 2.3 mol
then mol of O₂ = 2.3 mol ÷ 4
= 0.575 mol
mass of O₂ = moles of O₂ × molar mass of O₂
= 0.575 mol × (16 × 2) g/mol
= 18.4 g
Arm. The center is the yellow, in the very middle. I hope this helps.
