Answer:
119.85 grams Br or 120. grams Br (sig figs)
Explanation:
1.50 moles Br          79.90 g Br
--------------------- x ------------------------ = 119.85 grams Br or 120 grams Br (sig figs)
                                      1 mole
 
        
             
        
        
        
If the results of the experiment on repeating are not same, it shows the results are not standard, there are some factors, which are not constant
 
        
             
        
        
        
Answer:
1.02mole
Explanation:
The reaction equation is given as: 
      2NaOH  +  H₂SO₄ →  Na₂SO₄  + 2H₂O
Given: 
Mass of H₂SO₄  = 50g
Unknown: 
Number of moles of NaOH = ? 
Solution: 
To solve this problem, we first find the number of moles of the acid given; 
   Number of moles  = 
 
Molar mass of H₂SO₄ = 2(1) + 32 + 4(16)  = 98g/mol 
Now; 
    Number of moles = 
   = 0.51mole 
From the balanced reaction equation: 
        1 mole of H₂SO₄ will be neutralized by 2 mole of NaOH 
      0.51 mole of H₂SO₄ will be neutralized by 2 x 0.51  = 1.02mole of NaOH