【简答题】工业制备氯化铜时,将浓盐酸用蒸气加热至80 ℃左右,慢慢加入粗CuO粉末(含杂质Fe 2 O 3 、FeO),充分搅拌,使之溶解,得一强酸性的混合溶液,现欲从该混合溶液中制备纯净的CuCl 2 溶液,采用以下步骤[参考数据:pH≥9.6时,Fe 2 + 完全水解成Fe(OH) 2 ;pH≥6.4时,Cu 2 + 完全水解成Cu(OH) 2 ;pH≥3.7时,Fe 3 + 完全水解成Fe(OH) 3...
【简答题】(9分)某校一化学实验小组通过实验分析,确定一红色粉末为Fe 2 O 3 和Cu 2 O的混合物。 己知:①Cu 2 O溶于稀硫酸生成Cu和CuSO 4 ,②Cu 2 O在空气中加热生成CuO。 (1)实验小组欲用加热法测定Cu 2 O的质量分数。取 a g固体粉末在空气中充分加热,待质量不再变化时,称其质量为 b g( b > a ),则混合物中Cu 2 O的质量分数为__________。 (...
【单选题】International football matches always_____better understanding between countries all over the world. [ ]
【简答题】工业制备氯化铜时,将浓盐酸用蒸气加热至80℃左右,慢慢加入粗CuO粉末(含杂质Fe 2 O 3 、FeO),充分搅拌,使之溶解,得一强酸性的混合溶液,现欲从该混合溶液中制备纯净的CuCl 2 溶液,采用以下步骤[参考数据:pH≥9.6时,Fe 2+ 完全水解成Fe(OH) 2 ;pH≥6.4时,Cu 2+ 完全水解成Cu(OH) 2 ;pH≥3.7时,Fe 3+ 完全水解成Fe(OH) 3 ].请...
【简答题】A theme in new trade theory is that the__________ of trade we observe in the world economy may be the result of economies of scale and ____________ advantages. First-mover advantages are the economic ...
【多选题】2018年无公害农产品认证制度进行了改革,以下属于改革内容的是( )。
【单选题】The result of the new study will help _ get a better understanding on children's TV viewing.
A.
the movie stars C. the advertisers
B.
the children viewers D. the educators
【多选题】2018年无公害农产品认证制度进行了改革,以下属于改革内容的是( )。(多选)
【单选题】下列哪项不是强直性脊柱炎的特点?( )
C.
以非对称性的下肢大关节炎为主,极少累及手关节
【单选题】The author suggests that a better understanding of the ancient settlements on the sea bed may ______.
A.
inspire more young people to take up archaeology
B.
modify the attitudes of the British to their country's history
C.
provide confirmation about the dangers of global warming
D.
alter the perception other countries have about Britain