how does a balanced chemical equation demonstrate the law of conservation of mass?
a. it shows that only physical changes follow the law of conservation of mass
b. it shows that no atoms have been gained or lost during the reaction
c. it shows that the properties of the elements stay the same after the reaction
d. it shows that all compounds remain bonded after the reaction
b. it shows that no atoms have been gained or lost during the reaction
which procedure could be used to demonstrate that matter is conserved during a physical change?
a. find the mass of a piece of ice. let the ice melt. find the mass of the liquid water.
b. find the mass of a raw egg. cook the egg. find the mass of the cooked egg.
c. find the mass of a cup of water. boil the water find the mass of the water that remains.
d. find the mass of an apple. cut the apple and remove the core. find the mass of the remaining apple.
c. find the mass of a cup of water. boil the water and find the mass of the water that remains.
one molecule of bromine (br2) and two molecules of potassium chloride (KCI) combine in a reaction. how many atoms are in the products?
a. four
b. six
c. two
d. three
To determine the number of atoms in the products of the reaction, we need to understand the stoichiometry of the reaction.
The balanced chemical equation for the reaction is:
Br2 + 2KCl -> 2KBr + Cl2
Thus, one molecule of bromine (Br2) reacts with two molecules of potassium chloride (KCl) to produce two molecules of potassium bromide (KBr) and one molecule of chlorine gas (Cl2).
From the equation, we can see that in the products, there are a total of six atoms:
- Two atoms of potassium (K) in each molecule of potassium bromide (2KBr)
- Two atoms of bromine (Br) in each molecule of potassium bromide (2KBr)
- Two atoms of chlorine (Cl) in each molecule of chlorine gas (Cl2)
Therefore, the correct answer is b. six.
use the unbalanced chemical equation to answer the question.
2NaHCO3 → Na2CO3 + CO2
Which of the following can be added to the products to balance the equation?
a. H2
b. CH2OH
c. O2
d. H2O
To balance the equation, we need to ensure that the number of atoms of each element is the same on both sides of the equation.
Looking at the unbalanced equation:
2NaHCO3 -> Na2CO3 + CO2
We can see that there are 2 sodium (Na) atoms, 2 hydrogen (H) atoms, 2 carbon (C) atoms, and 6 oxygen (O) atoms on the left-hand side (reactant side). On the right-hand side (product side), there are 2 sodium (Na) atoms, 1 carbon (C) atom, and 3 oxygen (O) atoms.
To balance the equation, we can add water (H2O) to the products. This will provide the needed hydrogen (H) and oxygen (O) atoms to balance the equation.
Thus, the correct answer is d. H2O can be added to the products to balance the equation.