Indicate the concentration of each present in the solution formed by mixing

Im very confused apon the process of doing these problems, i will offer more points to anyone who can answer them for me
1)42.0 mL of 0.130 M NaOH and 37.6 mL of 0.420 M NaOH
2)44.0 mL of 0.100 M and Na2SO4 and 25.0 mL of 0.190 M KCl
3)3.90 g KCl in 75.0 mL of 0.290 M Ca2Cl solution, assume that the volumes are additive

1)
find moles
(0.0420 L) (0.130 M NaOH)= 0.00546 moles of NaOH
(0.0376 L) (0.420 M NaOH) = 0.01579 moles NaOH

0.00546 moles of NaOH + 0.01579 moles NaOH = 0.02125 moles NaOH

find molarity in that new total volume of 79.6 ml:
(0.02125 moles NaOH) / 0.0796 L = 0.26698 M
rounded to 3 sig figs that 0.267 Molar NaOH
which releases
0.267 M Na+
&
0.267 M OH-

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2)
0.100 M Na2SO4 is diluted from 44.0 mLto a total of 69.0 mL
(0.100 M Na2SO4) (44/69) = 0.0638 Molar Na2SO4
which releases
twice as much Na+ = 0.128 M Na+
&
0.0638 M (SO4)-2


0.190 M KCl is diluted from 25.0 ml to a total of 69.0 ml
(0.190 M KCl) (25.0 / 69.0) = 0.00688 Molar KCl
which releases
0.00688 M K+
&
0.00688 M Cl-

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3)
use molar mass to find moles
(3.90 g KCl) (1 mole KCl / 74.55 grams) = 0.0523 moles of KCl

find Molarity
(0.0523 moles of KCl) / 0.0750 Litres = 0.698 Molar KCl
which releases
0.698 Molar K+
&
0.698 Molar Cl-



& 0.290 M CaCl2 solution releases
0.290 M Ca+2
&
twice that in Cl- = 0.580 M Cl-

for combining the Cl- , & restating the Ca++ & the K+
0.698 Molar K+
0.290 M Ca+2
0.580 M Cl- + 0.698 Molar Cl- = 1.278 M Cl-

(does the edit answer your email?)

1) (42.0mL * 0.130M + 37.6ml * 0.420M)/(42.0 + 37.6)mL
= answer in M (should be ~ 0.280 M) by eyeball test

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2) (0.100*44.0)/(44.0+25.0)= conc of Na2SO4 in M ~0.6 to 0.7

(0.190 *25)/(44.0 +25.0) = conc of KCl in M about ~~0.12

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figure out Molecular Weight of KCl (MW)

amount of volume of your KCl is 3.90 g / (density in g/cm^3 (look it up) ) = KCL Vol

MOLES of KCl = (3.90 g/MW in grams)

new volume = KCL Vol (do above calc) + 75.0 ml = NEW VOL (in ml)



conc of Cl is (MOLES of KCl (above calc) + 0.290 M * 75ml/1000ml/L) /((NEW VOL in ml)*1000 ml/L)

conc of Ca is 2*0.290 M * 75.0/NEW VOL

conc of K is (MOLES of KCl (above calc) ) /((NEW VOL in ml)*1000 ml/L)