\(m_{dd}=\dfrac{40}{20\%}=200\left(g\right)\)

nCO2=0,4(mol)

a) PTHH: 2 NaOH + CO2 -> Na2CO3 + H2O

0,8_________0,4________0,4(mol)

=> mNaOH=0,8.40=32(g) 

=>C%ddNaOH=(32/200).100=16%

b) mddNa2CO3=mddNaOH+mCO2=200+0,4.44=217,6(g)

mNa2CO3=106.0,4=42,4(g)

=>C%ddNa2CO3=(42,4/217,6).100=19,485%

Chúc em học tốt!

n_CO2=8,96/22,4=0,4mol

a/ CO₂+2NaOH→Na₂CO₃+H₂O

   0,4      0,8           0,4         0,4

m_NaOH=0,8.40=32g

C%dd_NaOH=m_ct/_mdd.100%=32/200.100%=16%

b/m_CO2=0,4.44=17,6g

Theo định luật bảo toàn khối lượng:

m_CO2+m_NaOH=m_Na2CO3

17,6g+200g=217,6g

m_Na2CO3=0,4.106=42,4g

C%ddNa2CO3=m_ct/mdd.100%=42,4/217,6.100=19,4852g

\(n_{CuSO4}=\dfrac{16\%.50}{100\%.160}=0,05\left(mol\right)\)

Pt : \(CuSO_4+2NaOH\rightarrow Cu\left(OH\right)_2+Na_2SO_4\)

       0,05-------->0,1---------->0,05--------->0,05

a) \(C\%_{ddNaOH}=\dfrac{0,1.40}{250}.100\%=1,6\%\)

b) \(m_{ddspu}=50+250-0,05.98=295,1\left(g\right)\)

\(C\%_{Na2SO4}=\dfrac{0,05.142}{295,1}.100\%=2,41\%\)

\(n_{CuSO_4}=\dfrac{m_{dd}\cdot C\%}{100\cdot M}=\dfrac{50\cdot16\%}{100\cdot\left(64+32+16\cdot4\right)}=0,05\left(mol\right)\)

\(PTHH:CuSO_4+2NaOH\rightarrow Cu\left(OH\right)_2+Na_2SO_4\)

                     1                  2                    1                    1

                   0,05              0,1                 0,05               0,05 (mol)

\(a)C\%_{NaOH}=\dfrac{n\cdot100\cdot M}{m_{dd}}=\dfrac{01\cdot100\cdot\left(23+16+1\right)}{250}=1,6\%\)

\(b)m_{dd-sau-pư}=m_{dd_đ}+m_{ct_đ}-m\downarrow-m\uparrow\)

\(=50+250-\left(0,05\cdot23+32+16\cdot4\right)=294,05\left(g\right)\)

\(C\%_{Na_2SO_4}=\dfrac{n\cdot100\cdot M}{m_{dd}}=\dfrac{0,05\cdot100\cdot\left(23\cdot2+32+16\cdot4\right)}{294,05}\approx2,41\%.\)

nCuSO4​=100%.16016%.50​=0,05(mol)

Pt : ����4+2����→��(��)2+��2��4CuSO4​+2NaOH→Cu(OH)2​+Na2​SO4​

       0,05-------->0,1---------->0,05--------->0,05

a) �%������=0,1.40250.100%=1,6%C%ddNaOH​=2500,1.40​.100%=1,6%

b) ������=50+250−0,05.98=295,1(�)mddspu​=50+250−0,05.98=295,1(g)

�%��2��4=0,05.142295,1.100%=2,41%C%Na2SO4​=295,10,05.142​.100%=2,41%

\(m_{NaOH}=200.15\%=30\left(g\right)\)

\(m_{ddNaOH\left(10\%\right)}=\dfrac{30.100}{10}=300\left(g\right)\)

\(\Rightarrow m_{H_2Othêm}=300-200=100\left(g\right)\)

ta có: \(\dfrac{m_{NaOH}}{200}.100\%=15\%\)

=> m_NaOH = 30(g) (1)

Ta có:

\(\dfrac{m_{NaOH}}{200}.100\%=10\%\)

=> m_NaOH = 20(g) (2)

Ta có (1): 30 + \(m_{H_2O}=200\left(g\right)\)

=> \(m_{H_2O}=170\left(g\right)\)

ta có (2): \(20+m_{H_2O}=200\left(g\right)\)

=> \(m_{H_2O}=180\left(g\right)\)

Vậy khối lượng nước cần để thu đc dung dịch NaOH 10% là:

180 - 170 = 10(g)

a) \(m_{NaOH}=\dfrac{60.20}{100}=12\left(g\right)\)

\(C\%_{dd.sau.khi.pha}=\dfrac{12}{60+40}.100\%=12\%\)

b) \(C\%_{dd.sau.khi.pha}=\dfrac{12+12}{60+12}.100\%=33,33\%\)

60g dd 20% có 60.20%=12g NaOH, 60-12=48g H2O

a, Pha thêm 40g H2O , ta có 88g H2O

→C%NaOH=12.100:88=12,64% 

b) 

tan thêm 12 g

=>m NaOH=24g

=>C%=\(\dfrac{24}{60+12}100\)=33,33%

\(m_{NaOH}=\dfrac{60.20}{100}=12\left(g\right)\\ a,m_{\text{dd}}=60+40=100\left(g\right)\\ C\%=\dfrac{12}{100}.100\%=12\%\\ b,m_{NaOH}=12+12=24\left(g\right)\\ C\%=\dfrac{24}{60}.100\%=40\%\)

\(n_{NaOH}=\dfrac{10.200}{100.40}=0,5mol\\ 3NaOH+FeCl_3\rightarrow Fe\left(OH\right)_3+3NaCl\)

0,5                0,25           0,25               0,5

\(m_{dd}=200+100-0,25.107=273,25g\\ C_{\%NaCl}=\dfrac{0,5.58,5}{273,25}\cdot100=10,7\%\)

đề thiếu C% của FeCl₃ không vậy bạn

Câu 1:

VddHCl(sau)= 300+200=500(ml)=0,5(l)

nHCl= (200/1000).2= 0,4(mol)

=> C_MddHCl(sau) = 0,4/0,5= 0,8(M)

Câu 2:

mNaOH= 40.40%= 16(g)

mddNaOH(sau)= 260+40=300(g)

=> C%ddNaOH(sau)= (16/300).100 \(\approx\) 5,333%

Gọi C_%(Y)=x (%)

Áp dụng quy tắc đường chéo ta có

200g dd NaOH 10%                           20 - x

                                                  x

300g dd NaOH 20%                              x-10

=>\(\frac{200}{300}\)= \(\frac{20-x}{x-10}\)

=> x=16 (%)

Vậy nồng đọ % của dd Y là 16%

Đây là.môn hoá nhé