The document discusses the definitions and properties of bases and alkalis. It provides examples of metal oxides and metal hydroxides that are bases, including copper(II) oxide, magnesium oxide, sodium hydroxide, and potassium hydroxide. It defines an alkali as a base that is soluble in water, and explains that alkalis ionize in water to produce hydroxide ions. When testing an alkali with red litmus paper, the paper will turn blue. Alkalis also have a bitter taste and slippery feel, and a pH value greater than 7.

1. BASE Can you name a
few examples of
metal oxides and
metal hydroxides?
But teacher,
what is an
ALKALI?
That's right,
John!
Hi, everyone!
Today let's
learn about
BASE and
ALKALI.
Metal oxides such as
copper(II) oxide, CuO
and magnesium oxide,
MgO.
An alkali is a
BASE that is
SOLUBLE IN
WATER.
A BASE is a
substance that
REACTS WITH
ACIDS to produce
SALT and WATER
ONLY.
by estherannerandyy
Most bases are
METAL OXIDES and
METAL HYDROXIDES.
And metal hydroxides
are such as sodium
hydroxide, NaOH and
potassium hydroxide,
KOH.
Very good,
Sam!
Potassium
hydroxide, KOH is
an alkali because it
is soluble in water.

2. Now let's form the
ionisation equation
of sodium hydroxide,
NaOH.
An alkali is a
chemical substance
that ionise in
water to produce
hydroxide ions,
OH-.
Let me try, teacher.
Sodium hydroxide,
NaOH ionises in
water to produce
sodium ion, Na+ and
hydroxide ions OH-.
So, the equation of
ionisation of sodium
hydroxide is
NaOH -> Na+ + OH-
Very good,
Maya!
Next, does anyone know
how an alkali tastes
like? If we test an alkali
with red litmus paper,
what will happen?
Oh, I know!
Alkali tastes
BITTER,
yuck!
Alkali also
turns red
litmus paper
to BLUE

3. Yes, strong alkali
can be
CORROSIVE.
Alkali FEELS
SLIPPERY too!
That's right,
Charlie! Teacher, what's
the pH value for
an alkali?
Oh, I can't
wait to learn
about this
one!
Are alkalis
corrosive,
teacher?
That's correct, Charlie!
Next, let's see what
are the uses of ACIDS
and ALKALIS in our
DAILY LIFE.
If I'm not mistaken,
an alkali has a pH
value MORE
THAN 7.