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HT
3
12 tháng 8 2021
Bài 8:
Đặt CTTQ oxit kim loại hóa trị III là A2O3 (A là kim loại)
nH2SO4=0,3(mol)
mNaOH=24%. 50= 12(g) => nNaOH=0,3(mol)
PTHH: 2 NaOH + H2SO4 -> Na2SO4 + 2 H2O
0,3________0,15(mol)
A2O3 +3 H2SO4 -> A2(SO4)3 +3 H2
0,05___0,15(mol)
=> M(A2O3)= 8/0,05=160(g/mol)
Mặt khác: M(A2O3)=2.M(A)+ 48(g/mol)
=>2.M(A)+48=160
<=>M(A)=56(g/mol)
-> Oxit cần tìm: Fe2O3
12 tháng 8 2021
Bài 7:
mHCl= 547,5. 6%=32,85(g) => nHCl=0,9(mol)
Đặt: nZnO=a(mol); nFe2O3=b(mol) (a,b>0)
PTHH: ZnO +2 HCl -> ZnCl2+ H2O
a________2a_______a(mol)
Fe2O3 + 6 HCl -> 2 FeCl3 + 3 H2O
b_____6b____2b(mol)
Ta có hpt:
\(\left\{{}\begin{matrix}81a+160b=28,15\\2a+6b=0,9\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=0,15\\b=0,1\end{matrix}\right.\)
=> mFe2O3=0,1.160=16(g)
=>%mFe2O3=(16/28,15).100=56,838%
=>%mZnO= 43,162%
Ai làm hộ em với ạ e cần gấp ạ
15 tháng 6 2021
41.C
42.B
43.A
44.C
45.D
46. MK KO BIẾT
47.C
48.B
49. MK KO BIẾT
50.A
❤ HOK TT ❤
CM
0
11 tháng 9 2023
I. Write sentences with the cues given
1. Mai / usually / listen / K - pop music / free time.
→ Mai usually listens to K-pop music in her free time.
2. when / I / be / a child / I / enjoy / play / computer games
→ When I was a child, I enjoyed playing computer games.
3. my father / spend / most / spare time / look after / the garden
→ My father spends most of his spare time looking after the garden.
4. watching TV / most / popular / leisure activity / Britain ?
→ Is watching TV the most popular leisure activity in Britain?
5. many teenagers / addicted / the Internet / computer games
→ Many teenagers are addicted to the Internet and computer games.
6. she / get / hooked / the medical drama / after / watch / the first people
→ She got hooked on the medical drama after watching the first episode.
7. most / my friends / prefer / play sports / to / surf the net
→ Most of my friends prefer to play sports rather than surf the net.
8. today's world / teenagers / rely / technology / more / the past
→ In today's world, teenagers rely on technology more than in the past
II. Write the second sentences so that it has a similar meaning to the first one
1. It takes us more than two hours to see the film " Avatar "
→ The film " Avatar " requires more than two hours of our time to watch.
2. She likes to hang out with friends on Saturday evening
→ She's interested in socializing with friends on Saturday evening