原文由 echochen814 发表:
精确到0.01mg指的是误差范围为0.01mg,即称取的原料应该为9.99到10.01之间.
既然说了是精确称取,那就不是about了,要用exactly这类的词来纯强调准确性.
支持这种说法,不能再about了。
粗略称量:
Weigh approximately 0.1 g of potassium chloride and place in a beaker.
精确的说法:
Place exactly 0.1646 g of sodium chloride in a 1-l volumetric flask.
Weigh the cylinder to the nearest 0.1 g and mount it as shown in Fig. 4.
Weigh the beaker and residue to the nearest 0.1 mg.
Weigh approximately 45 g of potassium hydroxide pellets into a 100-mL volumetric flask.
Weigh 1.571 g ± 0.1 mg CuSO4 5H2O and transfer to a 1000-mL volumetric flask.
Weigh out 17 gms of silver nitrate and transfer to a 2 litre beaker.
Accurately weigh a clean dry stoppered 250 ml conical flask W1.
Accurately weigh a clean oven-dried porosity four sintered glass crucible W1.
Accurately weigh a clean oven-dried porosity four sintered glass crucible – weight ‘W1’.
Dissolve 1.9069 g KCl (element fraction K = 0.5244) dried at 110¡ãC, weighed accurately to at least four significant figures, in water, and dilute to volume in a 1,000 mL volumetric flask with water.