a)

$2K + 2H_2O \to 2KOH + H_2$

b)

n K = 3,9/39 = 0,1(mol)

Theo PTHH :

n H2 = 1/2 n K = 0,05(mol)

=> V H2 = 0,05.22,4 = 1,12(lít)

c)

m dd sau pư = m K + m nước - m H2 = 3,9 + 36,2 - 0,05.2 = 40(gam)

C% KOH = 0,1.56/40 .100% =14%

`Zn + 2HCl -> ZnCl_2 + H_2`

`0,1`    `0,2`                           `0,1`     `(mol)`

`n_[Zn]=[6,5]/65=0,1(mol)`

`a)V_[H_2]=0,1.22,4=2,24(l)`

`b)C%_[HCl]=[0,2.36,5]/200 . 100 =3,65%`

`Zn + HCl -> ZnCl_2 + H_2` `\uparrow`

`n_(Zn) = (6,5)/65 = 0,1 mol`.

`n_(H_2) = 0,1 mol`.

`V(H_2) = 0,1 xx 22,4 = 2,24l`.

`C%(HCl) = (0,2.36,5)/200 xx 100 = 36,5%`.

\(n_{Na}=\dfrac{6,9}{23}=0,3\left(mol\right)\\ 2Na+2H_2O\rightarrow2NaOH+H_2\\ n_{H_2}=\dfrac{0,3}{2}=0,15\left(mol\right)\\ a,V_{H_2\left(đktc\right)}=0,15.22,4=3,36\left(l\right)\\ b,m_{ddsaup.ứ}=m_{Na}+m_{H_2O}-m_{H_2}=6,9+100-0,15.2=106,6\left(g\right)\)

n_Na = 9.2/23 = 0.4 (mol) 

2Na + 2H₂O => 2NaOH + H₂

0.4.........................0.4.......0.2

V_H2 = 0.2 * 22.4 = 4.48 (l) 

m_NaOH = 0.4 * 40 = 16 (g) 

m_dd = 9.2 + 100 - 0.2 * 2 = 108.8 (g) 

C% _NaOH = 16 / 108.8 * 100% = 14.71%

PTHH: \(Na+H_2O\rightarrow NaOH+\dfrac{1}{2}H_2\uparrow\)

Ta có: \(n_{Na}=\dfrac{9,2}{23}=0,4\left(mol\right)\)

\(\Rightarrow\left\{{}\begin{matrix}n_{NaOH}=0,4\left(mol\right)\\n_{H_2}=0,2\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}m_{NaOH}=0,4\cdot40=16\left(g\right)\\V_{H_2}=0,2\cdot22,4=4,48\left(l\right)\\m_{H_2}=0,2\cdot2=0,4\left(g\right)\end{matrix}\right.\)

Mặt khác: \(m_{dd\left(saup/ứ\right)}=m_{Na}+m_{H_2O}-m_{H_2}=108,8\left(g\right)\)

\(\Rightarrow C\%_{NaOH}=\dfrac{16}{108,8}\cdot100\%\approx14,71\%\)

nNa=9,2/23=0,4(mol).

PTPƯ: 2Na (0,4)   +      2 H2O(0,4)----> 2NaOH (0,4)+    H2(0,2).

a)VH2= 0,2.22,4=4,48(lít).

mNaOH= 0,4.40=16(g).

b)mH2=0,2.2=0,4(mol).

mdd(sau pư)=mNa+mH2O-mH2=9,2+100-0,4=108,8(g)

C%ddNaOH=16/108,8.100=14,705%.

\(n_K=\dfrac{7,8}{39}=0,2\left(mol\right)\)

a) Pt : \(2K+2H_2O\rightarrow2KOH+H_2\)

           0,2                      0,2       0,1

b) \(V_{H2\left(dktc\right)}=0,1.22,4=2,24\left(l\right)\)

c) \(m_{KOH}=0,2.56=11,2\left(g\right)\)

d) 

\(C\%_{KOH}=\dfrac{11,2}{100}.100\%=11,2\%\)

 Chúc bạn học tốt

quỳ chuyển xanh

2K+2H2O->2KOH+H2

0,02---------------0,02--0,01

n K=0,02 mol

b) thiếu đề

c)

H2+CuO-to>Cu+H2O

0,01-0,01----0,01

n CuO=0,01 mol

=>pứ hết 

=>m Cu=0,01.64=0,64g

mình đg cần gấp

a) nNa = 4,6/23 = 0,2 (mol)

PTHH: 2Na + 2H2O -> 2NaOH + H2

Mol: 0,2 ---> 0,2 ---> 0,2 ---> 0,1

VH2 = 0,1 . 22,4 = 2,24 (l)

b) CMNaOH = 0,2/0,1 = 2M

c) mH2O = 100 . 1 = 100 (g)

mNaOH = 0,2 . 40 = 8 (g)

mH2 = 0,1 . 2 = 0,2 (g)

mdd = 100 + 8 - 0,2 = 107,8 (g)

C%NaOH = 8/107,8 = 7,42%