Answer:- 0.143 M
Solution:- HCl and NaOH reacts in 1:1 mol ratio as shown in the below reaction:

Let's calculate the initial moles of HCl and the moles of NaOH added to it:

= 0.075 mol HCl

= 0.025 mol NaOH
Since they react in 1:1 mol ratio, 0.025 mol of NaOH will react with 0.025 moles of HCl.
Remaining moles of HCl = 0.075 - 0.025 = 0.050
Total volume of the solution = 0.250 L + 0.100 L = 0.350 L
So, the concentration of HCl in the resulting solution = 
= 0.143 M
Hence, the concentration of HCl acid in the resulting solution is 0.143 M.
Citric acid has the molecular formula C6H8O7 so you can add the molar masses of the elements from the periodic table. C has a molar mass of 12.01 g/mol, H has 1.01 g/mol and O has 15.999 g/mol. Now you calculate the total molar mass= (6*12.01 + 8*1.01 + 7*15.999). This yields a molar weight of 192.124 g/mol (anhydrous)
Answer:
The mass of 2,50 moles of NaCl is 146, 25 g.
Explanation:
First we calculate the mass of 1 mol of NaCl, starting from the atomic weights of Na and Cl obtained from the periodic table. Then we calculate the mass of 2.50 moles of compound, making a simple rule of three:
Weight NaCl= Weight Na + Weight Cl= 23 g+ 35,5 g= 58, 5 g/ mol
1 mol ------ 58, 5 g
2,5 mol---x= (2,5 mol x 58, 5 g)/ 1 mol = <u>146, 25 g</u>