Chemistry Questions and Answers

Which of the changes are chemical changes? $\square$ Candle wax is melted. $\square$ A candle is burned. $\square$ A silver teapot turns black. $\square$ Two clear colorless salt solutions are mixed and a bright orange precipitate forms. $\square$ Sugar crystals are ground to a fine powder. Determine the charge on each ion in the given compounds, and name the compound. Spelling counts. $$ \mathrm{Mg}_{3} \mathrm{~N}_{2} $$ name: charges: Mg : $\mathrm{N}:$ Mg: N: $\mathrm{Al}_{2} \mathrm{~S}_{3}$ name: charges: $$ \mathrm{Al}_{2} \mathrm{~S}_{3} $$ name: $\square$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ $\qquad$ Consider the neutralization reaction $$ 2 \mathrm{HNO}_{3}(\mathrm{aq})+\mathrm{Ba}(\mathrm{OH})_{2}(\mathrm{aq}) \longrightarrow 2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l})+\mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq}) $$ A $0.110-\mathrm{L}$ sample of an unknown $\mathrm{HNO}_{3}$ solution required 50.1 mL of $0.200 \mathrm{M} \mathrm{Ba}(\mathrm{OH})_{2}$ for complete neutralization. What is the concentration of the $\mathrm{HNO}_{3}$ solution? concentration: Atoms that gain or lose electrons are called ions. What is the charge on a nitrogen ion that has 6 electrons and 7 protons? If a sulfur ion with 16 protons and 17 electrons loses one electron, what is the resulting charge? In aqueous solution, classify these compounds as strong acids, weak acids, strong bases, or weak bases. Strong acid Weak acid Strong base Weak base | | | | | | | | | --- | --- | --- | --- | --- | --- | --- | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |

Which of the following changes are chemical changes? $\square$ Gasoline is evaporated. $\square$ Water is heated up. $\square$ Water is frozen. $\square$ Gasoline is burned. $\square$ Water is boiled.

Which best describes activation energy? A. The maximum amount of energy required to end a chemical reaction. B. The amount of energy absorbed in an endothermic reaction. C. The minimum amount of energy required to start a chemical reaction. D. The amount of energy released in an exothermic reaction.

What is the ranking order of the degree of polarity of HF, HCl, HBr, and HI?

Complete the equation for the reaction of baking soda (sodium bicarbonate, NaHCO3) with vinegar (acetic acid, HC2H3O2). Include phase symbols. $$ \begin{aligned} & \mathrm{NaHCO}_{3}(s)+\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}(a q) \rightarrow \mathrm{NaC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}(a q)+\mathrm{H}_{2} \mathrm{O}(l)+\mathrm{CO}_{2}(g) \\ & \text {

Click the "draw structure" button to launch the drawing utility. The anion $\mathrm{O}_{2}{ }^{-}$does not obey the octet rule. Draw its Lewis structure and state the type of octet-rule exception. Indicate the values of nonzero formal charges and include lone pair electrons. # 00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

How many protons, neutrons, and electrons are there in a neutral atom of 43 K (potassium-43)?

Hydrogen chloride is a covalent compound. Which is a correct Lewis dot structure for HCl?

The common charges of an element can be related to the electron configuration of the element. Why would copper ions have two common charges?

How do you find the ionic charge of NO3?

Which one of the following is a weak acid? Select one: A. HC104 B. HNO3 C. HCI D. HI E. HF

Why isn't the pH at the equivalence point always equal to 7 in a neutralization titration?

What type of esters can undergo Claisen reactions? - All esters can undergo Claisen reactions. - Only esters with two hydrogen atoms on the acarbon can undergo Claisen reactions. - Only esters with three hydrogen atoms on the acarbon can undergo Claisen reactions. - Only esters with two or three hydrogen atoms on the acarbon can undergo Claisen reactions.

Determine the molecular geometry about each interior atom and make a sketch for C2H4 (skeletal structure: H2CCH2).

How do you calculate average molarity?

How is sugar dissolving in water a physical change?

Question: no one two three The Lewis structure of NO2 shows that nitrogen has bonding group(s) and nonbonding group(s). Therefore, it has a electron... | Bond angles in NO2NO2 and associate ions | | | --- | --- | | Species | Bond angle | | NO2NO2 | 134∘ | | NO2+NO2+ | 180∘ | | NO2-NO2- | 115∘ | | no | | | --- | --- | | one | | | two | | | three | | | four | | | linear | | | bent | | | trigonal planar | | | trigonal pyramidal | | | tetrahedral | | | 90° | | | 109.5° | | | 120° | | The Lewis structure of NO2 shows that nitrogen has bonding group(s) and nonbonding group(s). Therefore, it has a electron geometry and a molecular geometry. For this molecular geometry, the idealized bond angles are , and the bond angle is predicted to be than that because bonding groups are repelled by a lone electron than by a pair of bonding electrons. The Lewis structure of NO2+ shows that nitrogen has bonding group(s) and nonbonding group(s). Therefore, it has a electron geometry and a molecular geometry. For this molecular geometry, the idealized bond angles are .

What is the Lewis structure for NH4+?

How many valence electrons does a sodium, silicon, beryllium, and oxygen atom have?

Why is density considered a physical property rather than a chemical property of matter?

What is the charge of CH₃COO, also known as the acetate ion?

What is the correct Lewis structure for CN^- (cyanide ion)?

Identify the element with the electron configuration: $$1s^22s^22p^63s^23p^64s^23d^{10}4p^6.$$

What is the chemical formula for chlorine with its ionic charge?

What does mean a 94% enantiomeric excess? - ☐ The product contains 94% of one enantiomer and 6% of the other enantiomer - ☐ The product contains 94% of one enantiomer and 6% of other products - ☐ The product contains an enantiomer which is 94% pure. - ☐ The product contains 97% of one enantiomer and 3% of the other enantiomer

Part A: What are the electron and molecular geometries, respectively, for the carbonate ion, CO2−3 ​ ?

Caffeine's molecular formula is C8H10N4O2. The molar mass of caffeine is 194 g/mol. What is the percentage of carbon in caffeine?

Share at least one example of each element of conductivity. Include key points (about 3) and briefly share your experience about this activity.

Write the balanced chemical equation for the reaction of KHP with NaOH.

Identify the subshell from which an electron is removed to form a cation.

How many valence electrons does hydrogen have? A. 0 B. 1 C. 2 D. 3

The molecular geometry (shape) of the H3O+ ion is: A. octahedral B. trigonal planar C. trigonal pyramidal D. bent E. tetrahedral

4. The COOH group is called a carboxylic acid group. The second oxygen helps to stabilize the conjugate base after the hydrogen leaves by sharing the increased electron density. This makes it easier to break the O-H bond. Draw the following three Lewis structures, HCOOH, H2CO3 and CH3OH. Which of the structures would make for the strongest acid, and which would result in the weakest acid? Justify your response in a sentence below the structures you draw.

List all the elements that start with the letter D and X.

On the periodic table, gold has the atomic number 79. This means that: A. an atom of gold has 79 protons and electrons combined. B. gold can be found in 79 isotopes. C. gold was the 79th element discovered. D. an atom of gold has 79 protons.

Silver has an atomic number of 47. Give the number of protons, neutrons, and electrons in a neutral atom of the most common isotope, Ag-107.

What is the bond order of Li2− ? Express the bond order numerically.

Using the electron configuration, how many valence electrons does sulfur (S) have? HINT: Sulfur’s atomic number is 16.

Determine the electron geometry and molecular geometry of XeF4.

**Question:** The chemical formula for lead(II) nitrite is: Pb(NO₂)₂. How many oxygen atoms are in each formula unit of lead(II) nitrite? The chemical formula for lead(II) nitrite is: $$Pb(NO_2)_2$$ How many oxygen atoms are in each formula unit of lead(II) nitrite?