HOC24
Lớp học
Môn học
Chủ đề / Chương
Bài học
1) He does not let anyone smoke in his house
-------> He hardly allowed anyone not to smoke in his house
1) sitting
2) giving
3) turn
4) written
5) are watered
6) to tell
1) The boy holding a bunch of flowers is my best friend
2) Do you mind playinh the tape once more ?
3) I promise to buy you a beautiful present on my vacation
4) English is spoken all over the world
Gọi a là mNaCl cần thiết thêm vào
mct NaCl ban đầu =\(\dfrac{200.25}{100}\) = 50g
mct NaCl sau khi thêm = 50+a
mdd NaCl sau khi thêm = 200 +a
C% sau khi thêm = 30%
C% = \(\dfrac{mct.100}{mdd}\)
------> 30% = \(\dfrac{\left(50+a\right).100}{200+a}\)
-------> 5000 +100a =30.(200 +a )
--------> a= 14.28g
Ta có: mKCl thực tế = 61.25 . 80 :100 =49g
------> n KCl = 49 : 74,5 = 0,65 mol
a) 2KClO3 -----> 2KCl + 3O2
2 2 3
0,65 <-------- )0,65
mKClO3 = 0,65 . 122,5 = 79,625 mol
n HCl = 3,56 : 36,5 = 0,1 mol
Fe + 2HCl ------> FeCl2 + H2 Cu +HCl ------> Không phản ứng
1 2 1 1
0,05<---- 0,1 ------------> 0,05
mFe = 0,05 . 56 = 2,8 g
mCu = 10 - 2,8 = 7,2 g
%m Fe = 2,8 . 100 :10 = 28%
%mCu = 7,2 .100 :10 =72 %
VH2 = 0,05 .22,4 =1,12l
1) That book was published one year ago
2) The magazines are put on the shelf in the right corner of the library
3) These toys are sold in Disneyland and Hong Kong
4) These old clothes are collected by the poor children
5)These reports will be finished by him at five o' clock
6) Nam said he attended in the lecture in that night
mO2 = 12 - 7,2 = 4.8g -----> nO2 = 4,8 : 32 = 0,15 mol
2R + O2 ------> 2RO (nhiệt độ)
2 1 2
0,3<-----0,15
nR= 0,3 mol
mR = 7,2 g
---------> MR = 7,2 : 0.3 = 24 g ( Mg )
Vậy R là Mg