Answer:
A. Wipe down the glassware to remove any cleaning solvent.
Explanation:
· Remove stoppers and stopcocks when they are not in use. Otherwise, they may "freeze" in place. You can de-grease ground glass joints by wiping them with a lint-free towel soaked with ether or acetone. Wear gloves and avoid breathing the fumes. The deionized water rinse should form a smooth sheet when poured through clean glassware.
Answer:
the number of neutrons in above isotope = A - Z = 27 - 13 = 14. Note: The molar mass of aluminium, which is average of atomic masses of all isotopes = 26.981538 g/mol, since 13Al27 is the major isotope.
Explanation:
Answer:
Explanation:
Physical change is a temporary and reversible change in which the physical properties of the substance changes without altering the composition of the substance Eg Melting of ice while chemical change is a permanent and not so easily reversible change in which the identity of the substance is altered to produce one or more substances Eg Combustion
Answer:
Na₂CO₃•H₂O
Explanation:
After it is heated, the remaining mass is the mass of sodium carbonate.
30.2 g Na₂CO₃
Mass is conserved, so the difference is the mass of the water:
35.4 g − 30.2 g = 5.2 g H₂O
Convert masses to moles:
30.2 g Na₂CO₃ × (1 mol Na₂CO₃ / 106 g Na₂CO₃) = 0.285 mol Na₂CO₃
5.2 g H₂O × (1 mol H₂O / 18.0 g H₂O) = 0.289 mol H₂O
Normalize by dividing by the smallest:
0.285 / 0.285 = 1.00 mol Na₂CO₃
0.289 / 0.285 = 1.01 mol H₂O
The ratio is approximately 1:1. So the formula of the hydrate is Na₂CO₃•H₂O.
