Question

Indicate if the following statements are TRUE (T) or FALSE (F):

a. A 5% glucose solution can be made by dissolving 50 grams of glucose into one liter of water.
b. Mixing 25 grams NaCl with 100 grams of water will produce a 25% by weight solution.
c. Combustion reactions are endothermic D The products of an acid-base neutralization reaction are different acids and bases.
e. There is approximately 84.1% carbon in C8H18.
f. These ionic compounds are insoluble in water: Ba3(PO4)2, CuCO3 and Mn(OH)2.
g. One mole of Ca3(PO4)2 contains 6.022 x 1023 atoms of phosphorous.
h. One mole of Fe2O3 contains 55.85 grams of iron.
i. All compounds containing (SO4)2- are soluble in water.
j. Reaction between KI(aq) and NaCl(aq) forms a precipitate of NaI(s).
k. In this equation: Fe2O3 → Fe + CO2 the correct coefficients are 2, 2, 4, 3.
l. This is a combination reaction: CaCO3(s) + 133 kcal → CaO(s) + CO2(g)

Answer 1

a) T

b) T

c) F

d) F

e) T

f) T

g) T

h) F

I) F

j) F

k) F

l) F

Step-by-step explanation:

The w/v concentration is obtained from, mass/volume. Hence;

%w/v= 50/1000= 5%

In the %w/w we have;

25g/100 g = 25% w/w

In combustion reaction, energy is given out hence it is exothermic.

Neutralization reaction yields a salt and water

% by mass of carbon is obtained from;

8× 12/114 × 100 = 84.1%

All the ionic substances mentioned have very low solubility in water.

One mole of a substance contains the Avogadro's number of each atom in the compound.

There are two iron atoms so one mole contains 2× 55.85 g of iron.

Some sulphates such as BaSO4 are insoluble in water.

Halides are soluble in water hence NaI is soluble in water.

The equation does not balance with the given coefficients because the number of atoms of each element on both sides differ.

The equation represents a decomposition of calcium carbonate as written.