How much energy is required to raise the temperature of 3 g of silver from 15°C to 20°C?

Answer:

Cu

Explanation:

I got it right on my test.

The element with an atomic mass of about 63.5 amu is Copper, which has the chemical symbol Cu.

An atom with an average atomic mass of about 63.5 amu corresponds to the element Copper with the chemical symbol Cu. This is determined by consulting a periodic table where each element is listed with its respective atomic mass closest to the given value. The atomic mass is the weighted average of the masses of its isotopes, and in the case of copper (Cu), this is calculated from its two stable isotopes with mass numbers 63 and 65. Thus, the correct chemical symbol for the atom described with an atomic mass of 63.5 amu is Cu.

Final answer:

1. Reactants are favored. 2. A chemical reaction rate measures the change in amount of reactant per unit of time. 3. When an equilibrium reaction makes more moles of gas than it consumes, increasing the pressure favors the reactants.

Explanation:

1. If Keq = 4 x 10^-7, the equilibrium constant, then reactants are favored because the Keq value is very small, indicating that the concentration of products is much lower than the concentration of reactants.

2. A chemical reaction rate measures the change in the concentration of a reactant or product per unit of time, so the correct answer is C) change in amount of reactant per unit of time.

3. In an equilibrium reaction that makes more moles of gas than it consumes, increasing the pressure favors the side with fewer moles of gas. Therefore, the equilibrium will shift to the left, favoring the reactants.

4. Adding more water to the equilibrium reaction CO2 + H2O <--> H2CO3 will result in the equilibrium being pushed in the direction of the reactants because adding more water will decrease the concentration of H2CO3, favoring the formation of more CO2 and H2O.

5. A catalyst increases the reaction rate by providing an alternative reaction pathway with a lower activation energy, which leads to more successful collisions between particles. Therefore, the correct answer is A) more collisions between particles, so more successful collisions.

6. To shift the reaction 4HCl(g) + O2(g) <--> 2Cl2(g) + 2H2O(g) to the right, the equilibrium can be shifted by increasing the pressure, which will favor the side with fewer moles of gas, in this case the products. Therefore, the correct answer is A) increase of pressure.

The species PO₄⁻³, ICl₃, SF₄, and ClO₄⁻¹ require an expanded valence shell in their Lewis Structures as they contain central atoms that go beyond the octet rule by bonding with more than four atoms.

The species that require an expanded valence shell to represent their Lewis structures are PO₄⁻³, ICl₃, SF₄, and ClO₄⁻¹. These molecules contain central atoms (Phosphorus, Iodine, Sulfur, and Chlorine respectively) that go beyond the octet rule by utilizing their d-orbitals to bond with more than four other atoms.

For example, in the case of PO₄⁻³ (Phosphate), the central atom (Phosphorus) is bonded to four Oxygen atoms and carries a formal charge, leading it to utilize its 3d orbitals and thus expanding its valence shell. Similarly for ICl₃, SF₄, and ClO₄⁻¹the central atoms exceed the octet rule, necessitating the expansion of their valence shell.

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D) Chromium (Cr)

______________

The correct option is 2.

For a chemical equation to be balanced, the number of atoms of each element present in the reactants must be the same with that present in the products. If the number of atom of any element at any of the two side of the reaction is not the same, then the equation is not balanced. Looking at the options given above, it will be noticed that for option 2, the number of Sr atom at the reactant side is 1 while at the product side it is 2. This shows that the equation is not balanced.

The unbalanced chemical equation is [tex]\boxed{2.{\text{ Sr}} + {{\text{O}}_2} \to {\text{SrO}}}[/tex].

Further explanation:

Chemical reaction:

The chemical conversion of one set of substances into another is termed as chemical reaction. The substances that were originally present before the occurrence of chemical reaction are known as reactants whereas the substances that are formed once the reaction goes to completion are called products. Any chemical reaction involves the bond breaking between the reactants and new bond formations occur in products.

The chemical reaction in which equal number of atoms of the different elements is present in the reactant as well as in the product side is known as balanced chemical reaction. Law of mass and energy conservation are followed by each and every balanced equation.

1. [tex]{\text{C}} + {{\text{O}}_2} \to {\text{C}}{{\text{O}}_{\text{2}}}[/tex]  

On the reactant side,

Number of carbon atoms is 1 while that of oxygen atoms is 2.

On the product side,

Number of carbon atoms is 1 while that of oxygen atom is 2.

The number of atoms of each type is the same on both sides of the reaction and therefore this reaction is balanced.

2. [tex]{\text{Sr}} + {{\text{O}}_2} \to {\text{2SrO}}[/tex]  

On the reactant side,

Number of strontium atoms is 1 while that of oxygen atoms is 2.

On the product side,

Number of strontium atoms is 2 while that of oxygen atom is 2.

The number of strontium atoms on both sides of the reaction is not same and therefore this reaction is unbalanced.

3. [tex]{\text{6}}{{\text{H}}_2} + 3{{\text{O}}_2} \to {\text{6}}{{\text{H}}_2}{\text{O}}[/tex]  

On the reactant side,

Number of hydrogen atoms is 12 while that of oxygen atoms is 6.

On the product side,

Number of carbon atoms is 12 while that of oxygen atom is 6.

The number of atoms of each type is the same on both sides of the reaction and therefore this reaction is balanced.

4.  [tex]{{\text{H}}_2} + {{\text{H}}_2} + {{\text{O}}_2} \to {{\text{H}}_2}{\text{O}} + {{\text{H}}_2}{\text{O}}[/tex]

On the reactant side,

Number of hydrogen atoms is 4 while that of oxygen atoms is 2.

On the product side,

Number of hydrogen atoms is 4 while that of oxygen atom is 2.

The number of atoms of each type is the same on both sides of the reaction and therefore this reaction is balanced.

Learn more:

Answer details:

Grade: High School

Subject: Chemistry

Chapter: Chemical reactions and equations

Keywords: balanced, unbalanced, Sr, O2, H2, H2O, C, reaction, conversion, reactants, products, SrO, CO2.

Your answer is d ) a complex system

Answer: Government laboratories and educational institutions

Explanation:

Certain government institutions and educational institutions offers forensic anthropologists full time permanent jobs. These jobs are awarded on the basis of their research and teaching experience. They are placed as scientists or laboratory assistants in the laboratory and professors or lectarar in educational institutes.

Final answer:

Using the carbon-14 dating method, and knowing that the 14C in the fossil has decayed to 1/4 of its original amount, we can calculate that the plant was alive approximately 11,460 years ago.

Explanation:

In using carbon-14 dating to determine the age of a plant fossil, we utilize the known half-life of 14C which is approximately 5730 years. If the 14C has decayed to 1/4 of the original amount in the plant fossil, that means two half-lives have passed. As each half-life represents 5730 years, the age of the plant can be calculated by doubling this value. Therefore, we conclude that this plant was alive roughly 11,460 years ago.

Answer:

[tex]7,16.10^{24}[/tex]

Explanation:

We know that in 1 mole of any substances there are [tex]6,02. 10^{23}[/tex] atoms

This number ([tex]6,02. 10^{23}[/tex]) is a constant that is known as the avogadros number

if we know how many atoms are in a mole of chromium to calculate how many there are in 11.9 moles we apply a simple rule of three

[tex]1 mol Cr\longrightarrow 6,02.10^{23} atoms\\ 11.9 moles Cr\longrightarrow x\\x=\frac{(11.9)(6,02.10^{23})}{1}\\ x= 7,16.10^{24} atoms[/tex]

In 11.9 moles of chrome there are [tex]7,16.10^{24}[/tex] atoms

To find the total mass of a C3H8 sample with 6.72 × 1024 H atoms, we calculate the number of moles of C3H8 and multiply it by the compound's molar mass to get approximately 61.5 grams.

The question asks us to calculate the total mass of a sample of C3H8 (propane) given the number of H atoms in the sample. First, we determine the number of moles of H atoms by dividing the given number of H atoms by Avogadro's number (6.022 × 1023 atoms per mole), then use the molar ratio of H to C3H8 to find the moles of C3H8. We can then multiply the moles of C3H8 by its molar mass (the sum of the mass of 3 carbon atoms and 8 hydrogen atoms) to find the total mass of the sample.

Using the provided information, C3H8 has 8 H atoms per molecule. Therefore, if there are 6.72 × 1024 H atoms, that constitutes 6.72 × 1024 ÷ 8 = 8.4 × 1023 molecules of C3H8. One mole of C3H8 contains 6.022 × 1023 molecules, so the sample contains 8.4 × 1023 ÷ (6.022 × 1023) ≈ 1.395 moles of C3H8.

Next, we calculate the molar mass of C3H8: (3 × 12.011 amu for C) + (8 × 1.0079 amu for H) ≈ 44.1 g/mol. The total mass of the sample is therefore 1.395 moles × 44.1 g/mol = 61.5 grams.

Answer: 3 more electrons

Explanation: Generally elements with inert gas configuration are more stable. It is also called as Octet rule.

It tells that, elements which have electrons equal to atomic number of inert gases (2,8,10,18,36 etc) in their valency shell are exceptionally stable.

Here in our case, nitrogen has atomic number-7, 1s2 2s2 2p3

Here N has 5 electrons in valency shell , hence it needs 3 more electrons to get octet configuration.

So answer is 3 Electrons

The outer electron shell of nitrogen (N) contains 5 electrons. It would need to obtain 3 electrons to fill its shell with 8 electrons in order to have a stable outer electron shell.

An element's capacity to maintain its current state or withstand any changes under usual circumstances is referred to as stability. The fact that it guarantees an element's durability and versatility across a range of applications makes it a desirable property. Depending on the situation, stability can have a variety of meanings. Chemical stability, which refers to an element's resistance to reactions or decomposition when exposed to various chemical environments, is a crucial component of stability. Strong chemical bonds that take a lot of energy to break are common in elements with high chemical stability. The outer electron shell of nitrogen (N) contains 5 electrons. It would need to obtain 3 electrons to fill its shell with 8 electrons in order to have a stable outer electron shell.

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Orange juice is an acid, characterized by a pH level lower than 7. Its acidic nature is what gives it a sour taste, with citric acid and ascorbic acid being the main contributors. Lemon juice is usually even more acidic and sourer than orange juice. The correct answer is option: an acid.

Orange juice is an acid. The acidity of a substance can be measured by its pH level, with lower pH values indicating higher acidity. Because orange juice has a pH lower than 7, it is considered acidic. The sour taste of orange juice is due to citric acid and ascorbic acid (vitamin C), both of which are acids.

In contrast, substances with a pH higher than 7 are basic, with increased hydroxide ion (OH-) presence or proton (H+) acceptors. Water with a pH of 7 is considered neutral, neither acidic nor basic. Comparing orange juice to lemon juice in terms of acidity, lemon juice is typically more acidic due to its lower pH and higher concentration of citric acid, which is why it tastes more sour.

The empirical formula is C2H3O2, and the molecular formula is C6H9O6.

To determine the empirical formula and the molecular formula of an organic compound from combustion analysis, follow these steps:

Using the provided data:

Acetone is a covalent compound, whereas sodium chloride is an ionic compound.

Covalent compounds have strong bonds that do not break apart like ionic compounds do, and they do not conduct electric charge in solution.

Covalent compounds do not have strong attractions between molecules and so have very low melting points, unlike ionic compounds.

Answer: B

Explanation:

Answer:

a. the smallest unit of matter that maintains its chemical identity.

Explanation:

Answer:

A neutral

Explanation:

Because sea water is neutral

Answer:

a neutral

Explanation:

Another important chemical property of water is its neutral pH. Pure water has pH value of 7. It is neither acidic nor basic. Living organisms cannot survive in highly acidic or basic environments.