密度 and 重量: density and total weight
Read liquid density on an equal-volume basis and distinguish it from total weight. Higher density alone does not determine the weights of unequal amounts of liquid.
密度 compares equal volumes
密度, read みつど, means density. 二種類の液体の密度を実験で比べました。 says that someone experimentally compared the densities of two liquids.
For these liquids, density concerns how much mass is contained in the same volume. It is not simply a comparison of the total weights of a large tank of one liquid and a small cup of another.
重量 gives the whole object’s weight
重量, read じゅうりょう, means weight in these examples. 荷物の重量を量って記録した。 says that someone weighed the luggage and recorded its weight.
箱には中身を含む重量が書かれている。 says that the box is labeled with a weight that includes its contents. Keep the inclusion of the contents as part of the measurement’s scope.
Density alone does not give the total weight
Even if one liquid has higher density, you cannot rank the total weights without knowing how much of each is present. Distinguish a property compared at equal volume from the actual total amount.
To compare total weights, check the amount of liquid and whether the container is included. Do not transfer a density comparison directly into a comparison of the objects’ 重量.
If liquid A is denser than B, must the full weight of A’s container be greater?
Show the answer and why
No. You need conditions such as the volume present and whether the container is included. Density alone does not determine the actual total weight.