Question

module 8 assessment, ps1 - 2 (ps1 - 7) unit 2
ubuntu, the unsafe scientist, dropped solid sodium metal into a beaker of water.
sly the student were asked to make a prediction regarding the reaction that occurred and provide following solution:
$na(aq)+h_{3}o(aq)\to na(oh)_{3}(aq)+h_{2}(g)$

1. the formula for water is wrong as written: $h_{3}o(aq)$

it should be written as
a. $h_{2}o(aq)$
b. $h_{2}o(l)$
c. $h_{2}o(aq)$
d. $h_{2}o(l)$

1. because

a. water dissociates in water and becomes aqueous.
b. water is a liquid and has two hydrogens and one oxygen.
c. water is aqueous but has two hydrogens and one oxygen.
d. water is a liquid but is written correctly with three hydrogens and one

1. the formula is wrong for sodium hydroxide as written: $na(oh)_{3}(aq)$

it should be written as
a. $na(oh)_{3}(aq)$
b. $naoh(aq)$
c. $na(oh)_{2}(aq)$
d. $na_{2}oh(aq)$

1. because......

sodium makes a(n)

1. $1 +$ ion
2. $2 +$ ion
3. $3 +$ ion
4. $4 +$ ion

and hydroxide makes a(n)

1. $1 -$ ion
2. $2 -$ ion
3. $3 -$ ion
4. $4 -$ ion
5. write the correct overall balance equation for this reaction?

Explanation:

6)

Step1: Analyze the state of water

Water in this reaction is in liquid state. The correct formula for liquid water is \(H_2O(l)\).

7)

Step1: Understand the state of water

Water is a liquid in this reaction. It is not dissolved in water (so not aqueous, \(aq\)) and its formula is \(H_2O\) (two hydrogens and one oxygen).

8)

Step1: Determine the formula of sodium hydroxide

Sodium has a \(+ 1\) charge (\(Na^+\)) and hydroxide has a \(-1\) charge (\(OH^-\)). The formula for sodium hydroxide is \(NaOH\). In aqueous solution, it is \(NaOH(aq)\).

9)

Step1: Find the charge of sodium and hydroxide ions

Sodium (\(Na\)) loses one electron to form \(Na^+\) (a \(1+\) ion). Hydroxide (\(OH\)) has a charge of \(-1\) (a \(1 -\) ion).

10)

Step1: Write the un - balanced equation

The reaction between sodium (\(Na\)) and water (\(H_2O\)) forms sodium hydroxide (\(NaOH\)) and hydrogen gas (\(H_2\)). The un - balanced equation is \(Na + H_2O
ightarrow NaOH + H_2\).

Step2: Balance the hydrogen atoms

We have 2 hydrogen atoms in \(H_2\) and 1 in \(H_2O\) and \(NaOH\). Multiply \(H_2O\) and \(NaOH\) by 2: \(Na+2H_2O
ightarrow 2NaOH + H_2\).

Step3: Balance the sodium atoms

Now we have 1 sodium atom on the left and 2 on the right. Multiply \(Na\) by 2: \(2Na + 2H_2O
ightarrow 2NaOH+H_2\).

Answer:

1. b. \(H_2O(l)\)
2. b. Water is a liquid and has two hydrogens and one oxygen.
3. b. \(NaOH(aq)\)
4. a) \(1+\) ion and a) \(1-\) ion
5. \(2Na(s)+2H_2O(l)

ightarrow 2NaOH(aq)+H_2(g)\)