10. The more compact a metal is, the less brittle it becomes. -True? I'm confused about this one because of what the textbook says: "the more compact the atoms become, the harder the metal becomes. While the compactness makes the metal hard, a fracture on any boundary causes the metal to harden even more. This hardening also makes some metal more brittle."
5. How much of a compound would need to be mixed with 114 g of an element if the ratio of the element to the compound is 2 parts element to 1 part compound?
12. What is the major difference between ionic bonding and metallic bonding?
a. In metallic bonding the valence electrons are de-localized
b. In metallic bonding the electrons are held close to the cations
c. In ionic bonding the valence electrons are de-localized
d. In ionic bonding the electrons are held close to the cations
D?
18. When 2 hydrogen gas molecules are combined with 1 oxygen gas molecule, how many water molecules are created?
No idea..
Thanks!
10. The statement in the textbook is correct. When the atoms in a metal are more compact, the metal becomes harder. However, this increased hardness can also make the metal more brittle. So, the answer to whether a metal becomes less brittle with increased compactness depends on the context.
5. To determine how much of the compound needs to be mixed with 114 g of the element, we need to know the molar mass of both substances. Let's say the molar mass of the element is E g/mol and the molar mass of the compound is C g/mol.
Given the ratio of 2 parts element to 1 part compound, it means that the mass of the element is twice that of the compound. So, if we mix x grams of the compound, we would have 2x grams of the element.
We can set up a proportion using the molar masses and masses:
(E g/mol) / (C g/mol) = (2x g) / (x g)
Simplifying the equation:
2E = C
Therefore, the mass of the compound should be equal to the molar mass of the element.
12. The correct answer is a. In metallic bonding, the valence electrons are delocalized, meaning they are free to move throughout the entire metal lattice. This allows metals to conduct electricity and heat. In contrast, in ionic bonding, the valence electrons are transferred from one atom to another, creating ions. The resulting electrostatic attraction between the positive and negative ions holds them together in a crystal lattice.
18. When 2 hydrogen gas molecules (H2) combine with 1 oxygen gas molecule (O2), they react to form water (H2O). The balanced chemical equation for this reaction is:
2H2 + O2 → 2H2O
So, when the reaction is complete, two water molecules (H2O) are created.
10. The statement you mentioned from the textbook is correct. The more compact the atoms in a metal become, the harder the metal becomes. However, this increased hardness can also make the metal more brittle. When a metal is compact, the arrangement of atoms is closer, creating stronger bonds between them. This makes the metal harder. However, if a fracture occurs on any boundary within the metal structure, it can cause the metal to harden even more, making it more prone to brittleness and potential breakage. So, the statement in the textbook about the relationship between compactness, hardness, and brittleness in metals is accurate.
5. To figure out how much of a compound needs to be mixed with 114 g of an element, we need to know the molar masses of both the element and the compound. Let's assume we know the molar masses of the element and the compound. Given the ratio of 2 parts element to 1 part compound, we can set up a proportion to find the amount of compound needed.
Let X represent the mass of the compound:
(2 parts element / 1 part compound) = (114 g element / X g compound)
Cross-multiplying, we get:
2 * X = 1 * 114
Simplifying the equation, we have:
2X = 114
Dividing both sides by 2, we find:
X = 57
Therefore, 57 g of the compound would need to be mixed with 114 g of the element, in order to maintain the given ratio of 2 parts element to 1 part compound.
12. The major difference between ionic bonding and metallic bonding is related to the behavior of the valence electrons.
In ionic bonding, atoms transfer electrons to form ions. One atom loses electron(s) to become a positively charged cation, while another atom gains electron(s) to become a negatively charged anion. The resulting attraction between the positive and negative ions creates the ionic bond. In this type of bonding, the valence electrons are localized around the individual ions, not free to move throughout the entire solid. Therefore, option d) "In ionic bonding, the electrons are held close to the cations" is correct.
On the other hand, in metallic bonding, the valence electrons are delocalized, meaning they are not associated with any specific atom. Instead, they are free to move throughout the metal lattice. This movement of electrons allows metals to conduct electricity and heat efficiently. Therefore, option a) "In metallic bonding, the valence electrons are delocalized" is correct.
18. To determine the number of water molecules created when 2 hydrogen gas molecules (H2) combine with 1 oxygen gas molecule (O2), we need to consider the balanced chemical equation for the formation of water (H2O).
The balanced equation is:
2H2 + O2 → 2H2O
From the equation, we can see that for every 2 molecules of hydrogen gas (H2) and 1 molecule of oxygen gas (O2), 2 molecules of water (H2O) are formed.
Therefore, when 2 hydrogen gas molecules combine with 1 oxygen gas molecule, the result is 2 water molecules.