Reactions with sodium chloride and silver nitrate

What are the most important reactions with these substances?

Sodium chloride crystals [Wikimedia]

Sodi­um chlo­ride is a bi­na­ry com­pound (con­sist­ing of two el­e­ments), a salt formed by the al­ka­line NaOH and the strong acid HCl. NaCl have no col­or or smell, and so with­out con­duct­ing qual­i­ta­tive re­ac­tions and tests, it is im­pos­si­ble to de­ter­mine that sodi­um chlo­ride is present in a so­lu­tion. Prac­ti­cal­ly all com­pounds with sodi­um and chlo­ride ions are sol­u­ble.

Meth­ods of de­ter­min­ing the pres­ence of sodi­um ions in a so­lu­tion

The flame turns yellow when it meets NaCl [Wikimedia]

There are sev­er­al meth­ods for de­ter­min­ing the pres­ence of sodi­um ions in a so­lu­tion. For ex­am­ple, if you put crys­tals of sodi­um salt into a flame, the flame will turn yel­low. A re­ac­tion can also be held in the so­lu­tion – if you place a met­al wire soaked in a so­lu­tion of sodi­um salt, the flame changes its col­or to yel­low. The salt must not con­tain im­pu­ri­ties – oth­er cations of al­ka­line and al­ka­line earth met­al may con­ceal the col­or of the flame.

[How to get NaCl crys­tals from its so­lu­tion](https://youtu.be/Wh­H­GizrKqUU}

With potas­si­um di­hy­dro­gen an­ti­monate the sodi­um chlo­ride so­lu­tion gives the fol­low­ing re­ac­tion:

NaCl + КН₂S­bО₄ = NaН₂S­bО₄ + КCl.

White crys­talline sed­i­ment of NaН₂S­bО₄ forms. The re­ac­tion takes place in a neu­tral or weak al­ka­line medi­um with­out cations of oth­er groups or am­mo­ni­um ions.

Sodi­um salts re­act with uranyl zinc ac­etate Zn(UO₂)₃(CH₃СOО)₈ in the pres­ence of acetic acid as fol­lows:

NaCl + Zn(UO₂)₃(CH₃­COO)₈ + СН₃СООН + 9Н₂О = NaZn(UO₂)₃ (CH₃­COO)₉·9Н₂О + HCl.

NaZn(UO₂)₃ (CH₃COO)₉·9Н₂О crystals [Wikimedia]

More ex­per­i­ments with acids you can find here.

On a mi­cro­crys­tal glass, a yel­low crys­talline sed­i­ment forms that is *in­sol­u­ble in acetic acid. *It is im­por­tant that the so­lu­tion does not con­tain salts of heavy met­als.

Re­ac­tion be­tween sodi­um chlo­ride and sil­ver ni­trate

Sodi­um chlo­ride and sil­ver ni­trate in dis­solved form can re­act with each oth­er in nor­mal con­di­tions. Both salts are sol­u­ble, but the prod­uct of their re­ac­tion, sil­ver chlo­ride AgCl is a salt that is in­sol­u­ble in wa­ter, which pre­cip­i­tates af­ter re­ac­tion in a white curd-like sed­i­ment:

NaCl + Ag­NO₃ = NaNO₃ + AgCl.

This is the qual­i­ta­tive re­ac­tion for chlo­ride ions – sil­ver ions al­ways bond them into an in­sol­u­ble com­pound.

Silver chloride AgCl formation [Wikimedia]

If a qual­i­ta­tive re­ac­tion is used, usu­al­ly to de­tect the pres­ence of chlo­ride ions the fol­low­ing method is used:

To 4-5 drops of the salt so­lu­tion (in this case sodi­um chlo­ride), 0.5 ml of di­lut­ed ni­tric acid and 2-3 drops of sil­ver ni­trate so­lu­tion is added. On the sam­ple glass a white curd-like sed­i­ment forms, sol­u­ble in am­mo­ni­um.

How to de­ter­mine the con­cen­tra­tion of sodi­um chlo­ride by re­ac­tion

By the re­ac­tion of sodi­um chlo­ride with sil­ver ni­trate, not only the pres­ence of chlo­rine ions can be de­ter­mined, but also their con­cen­tra­tion. Titra­tion of a so­lu­tion of sodi­um chlo­ride is car­ried out with a so­lu­tion of sil­ver ni­trate with a known con­cen­tra­tion un­til the so­lu­tion turns yel­low-or­ange.

NaCl [Wikimedia]

1 ml of the so­lu­tion is tak­en, and an in­di­ca­tor added to it (in this case potas­si­um chro­mate can be used), and titrat­ed un­til the so­lu­tion turns yel­low-or­ange, af­ter which the vol­ume of sil­ver ni­trate used for titra­tion is cal­cu­lat­ed. By pro­por­tion from the **law of equiv­a­lents: **

(V(NaCl) • Cₙ(NaCl) = V(Ag­NO₃) • Сₙ(Ag­NO₃)), the con­cen­tra­tion of the ini­tial so­lu­tion can be cal­cu­lat­ed, as it is the only un­known val­ue in the pro­por­tion).

Titra­tion is of­ten used in quan­ti­ta­tive anal­y­sis to de­ter­mine con­cen­tra­tion of so­lu­tions. The re­ac­tion be­tween sodi­um chlo­ride and sil­ver ni­trate can also be used for both the quan­ti­ta­tive and qual­i­ta­tive de­ter­mi­na­tion of the con­tent of chlo­rine ions in a so­lu­tion.