Two compounds are placed in a beaker, and they undergo a chemical reaction. An investigator finds that the total mass after the compounds react is less than the sum of the masses before they react. Which statement explains this observation?

Question

• Some of the mass has been released as energy.
• Some of the mass has escaped as a gas.
• Some of the mass was used as new compounds were formed.
• Some of the mass was used as energy to start the reaction.

Answer 1

The correct statement that explains the observation that the total mass after the compounds react is less than the sum of the masses before they react is:

Some of the mass has escaped as a gas.

In many chemical reactions, particularly those that produce gases, some of the products may escape into the atmosphere, resulting in a loss of mass that can be measured after the reaction occurs.

Answer 2

How does a balanced chemical equation demonstrate the Law of Conservation of Mass?
• it shows that only physical changes follow the Law of Conservation of Mass
• it shows that the properties of the elements stay the same after the reaction
it shows that no atoms have been gained or lost during the reaction
• it shows that all compounds remain bonded after the reaction

Answer 3

The correct statement that explains how a balanced chemical equation demonstrates the Law of Conservation of Mass is:

It shows that no atoms have been gained or lost during the reaction.

A balanced chemical equation illustrates that the number of atoms of each element present before the reaction is equal to the number of atoms of those elements after the reaction, thus confirming that mass is conserved throughout the process.

Answer 4

Which procedure could be used to demonstrate that matter is conserved during a physical change?

• Find the mass of a cup of water. Boil the water. Find the mass of the water that remains.

• Find the mass of an apple. Cut the apple and remove the core. Find the mass of the remaining apple.

• Find the mass of a raw egg. Cook the egg. Find the mass of the cooked egg.

• Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.

Answer 5

The procedure that could be used to demonstrate that matter is conserved during a physical change is:

Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.

In this procedure, the ice undergoes a physical change (melting) and you can compare the mass of the ice before melting with the mass of the resulting water. According to the Law of Conservation of Mass, the mass should remain the same before and after the change, demonstrating that matter is conserved.

Answer 6

One molecule of bromine (Br) and two molecules of potassium chloride (KCI) combine in a reaction. How many atoms are in the products?
• six
• two
• three
• four|

Answer 7

To determine how many atoms are in the products of the reaction between one molecule of bromine (Br) and two molecules of potassium chloride (KCl), we first need to identify the components involved:

1. Bromine (Br): This is 1 molecule of bromine, containing 1 atom of bromine.
2. Potassium Chloride (KCl): Each molecule of KCl contains 1 potassium (K) atom and 1 chlorine (Cl) atom. Therefore, 2 molecules of KCl contain:
   • 2 K atoms (1 from each KCl)
   • 2 Cl atoms (1 from each KCl)

Now, if we sum the total number of atoms:

• From 1 bromine molecule: 1 Br atom
• From 2 KCl molecules: 2 K atoms + 2 Cl atoms = 4 atoms

Adding these together gives us:

• 1 Br atom + 2 K atoms + 2 Cl atoms = 1 + 2 + 2 = 5 atoms in total.

Thus, the products of this reaction will contain 5 atoms. However, none of the provided options (six, two, three, four) include this total. Please verify if the question pertains to a specific product in context or if there is additional information. If the reaction suggests forming a specific compound, the number of atoms may differ based on the compound formed. If we look at the individual reactions of the constituents, the atom count doesn't match the options given.

Answer 8

One molecule of bromine (Br) and two molecules of potassium chloride (KCI) combine in a reaction. How many atoms are in the products?
the options are:
• six
• two
• three
• four

Answer 9

Let's break down the reaction between one molecule of bromine (Br) and two molecules of potassium chloride (KCl) to find the total number of atoms in the products.

1. One molecule of bromine (Br) contributes:

   • 1 Br atom

2. Two molecules of potassium chloride (KCl) contribute:

   • Each KCl contains 1 potassium (K) atom and 1 chlorine (Cl) atom. Therefore, two KCl molecules contain:
     • 2 K atoms
     • 2 Cl atoms

Now, summing these up:

• From bromine: 1 Br atom
• From 2 KCl: 2 K atoms + 2 Cl atoms = 4 atoms

Adding them together:

• Total = 1 (Br) + 2 (K) + 2 (Cl) = 5 atoms

It appears there is inconsistency with the options given, as the total atoms calculated is 5. In the context or set of products, if this was meant to represent one specific product as a result of the reaction (for example, if Br reacted and formed a compound), the atom count may change, yet in the straightforward context of each molecular contribution, you'd count 5.

However, if we consider the overall chemical stoichiometry (assuming Br combines with KCl forming products like KBr, where we incorporate Cl's from each reactant molecule dealing with resultant compounds), it still contains distinct products whose atom number doesn’t simplify to fit the options listed directly.

If you want my best extrapolation involving typical ionic compound formation, based on common chemistry:

• If Br replaced Cl in a typical product formation (KBr) process and we think about representative atomic formulation summing those involved in new states, approximating even in dissolution/ion charging to representative species intertwines yet may not retain within the predators dimension count in transcription.

In summary, within basic evaluating, originally counting up all presented ultimately leads to 5 atoms, reconciling to clarify the provided answers contextually without additional context guidance doesn’t yield to assure a pre-typed selector.

Answer 10

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?
(1 point)
СН2ОН
Н20
02
Н2

Answer 11

To balance the unbalanced chemical equation \( 2 \text{NaHCO}_3 \rightarrow \text{Na}_2\text{CO}_3 + \text{CO}_2 \), we first analyze the equation:

• Reactants: 2 sodium (Na), 2 hydrogen (H), 2 carbon (C), and 6 oxygen (O) atoms (from 2 NaHCO3).
• Products: 2 sodium (Na), 1 carbon (C) (from Na2CO3), and 1 carbon (C) (from CO2), which totals 2 carbon atoms, 3 oxygen (O) (from Na2CO3) and 2 oxygen (O) (from CO2), which gives us 5 oxygen atoms total in the products.

Currently, the left side has:

• 2 Na
• 2 H
• 2 C
• 6 O

The right side has:

• 2 Na
• 1 C (in Na2CO3) + 1 C (in CO2) = 2 C total
• 3 O (in Na2CO3) + 2 O (in CO2) = 5 O total

We see that there are:

• 2 Na on both sides
• 2 C on both sides
• 2 H on the left and none on the right

To balance the products, we would need to add hydrogen atoms to the product side.

Given the provided options:

1. СH2OH (methanol) would introduce carbon and hydrogen, which we do not need for this specific balancing requirement.
2. H2O (water) would also introduce more hydrogen and oxygen but is more useful for balancing as it directly gives us hydrogen, which is currently lacking.
3. O2 (dioxygen) would introduce oxygen, which isn't needed as we have enough oxygen balancing from both sides if we think of the products fully in consideration.
4. H2 (hydrogen gas) would also add hydrogen, but water serves our purpose conveniently.

Thus, the best option to add to the products side would be:

H2O (water)

This would add exactly the necessary hydrogen to balance the chemical equation effectively.