<span>In a popular classroom demonstration, solid sodium is added to liquid water and reacts to produce hydrogen gas and aqueous sodium hydroxide. Balanced chemical equation for this reaction is given below.
Na-sodium , H2o- water, H-hydrogen gas and NaOH- aqueous sodium hydroxide.
Two atoms of Na react with two atoms of water and this reaction will give us H (hydrogen gas) and two atoms of NaOH (aqueous sodium hydroxide).
2Na + 2 H2o = H2 +2NaOH.</span>
Answer:
0.106 mol (3s.f.)
Explanation:
To find the number of moles, divide the mass of glucose (in grams) by its Mr. Glucose has a chemical formula of C6H12O6. To find the Mr, add all the Ar of all the atoms in C6H12O6.
Ar of C= 12, Ar of H= 1, Mr of O= 16
These Ar values can be found on the periodic table.
Mr of glucose= 6(12)+ 12(1) + 6(16)= 180
Moles of glucose
= mass ÷ mr
= 19.1 ÷ 180
= 0.106 mol (3 s.f.)
Lower the melting point
Explanation:
Salts helps to melt road by lowering the melting point. It acts as an impurity and generally, impurities low the melting point of substances.
Salts are used as an antifreeze.
- Water freezes at 0°C and forms ice/snow which can impede human and vehicular movement.
- When salt is added, it causes the depression of the freezing point by lowering it further.
- The freezing point is pegged back at -6°C.
- This way it takes more low temperature to freeze the water.
- The salt acts as an impurity and causes the depression of melting point and widening of the melting range.
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C6H6 is the
most insoluble in water as it is non polar in nature. HCL is highly soluble in
water as it is an electrolyte. Kbr is also highly soluble in water. NaCl
dissolves in water very quickly. CH3CH3OH is also totally soluble in water
because of the Hydrogen bonding formation. It is a well known fact that the
hydrocarbons do not easily mix with water. C6H6 being a strong hydrocarbon does
not mix with water. So among NaCl, KBr, CH3CH3OH, HCl and C6H6, the hydrocarbon
is the least soluble in water.
