化学
化学反应、化学计量、分子结构与元素性质。
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what type of substance reacts with limestone (caco₃) and produces carbo…
an acid
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question 12 1 pts a modern nickel coin is composed mainly of the elemen…
B. False
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the table below lists some acids and bases strong acids | weak acids | …
\( NH_3 + HNO_3 \)
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question 11 an alloy of iron and carbon. (one word...watch your spellin…
Steel
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question 10 what is the chemical formula for sodium hydroxide? (watch u…
NaOH
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what chemical is the main component of natural gas? (what were buring a…
Methane
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which factor influences both solubility and the rate of dissolution? ○ …
B. temperature
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an acid is a substance that increases the concentration of h₃o⁺ ions in…
A. $\ce{C6H5OH(aq)}$
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what is the arrhenius definition of a base? a substance that increases …
B. A substance that increases $\ce{OH-}$ concentration when it is dissolved in water
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question 8 1 pt what is another name for sodium hydroxide? (there are m…
caustic soda
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question 7 1 pt an alloy of copper and tin. (watch your spelling)
bronze
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which characteristic best identifies an arrhenius base? ○ it must donat…
B. It must accept protons from an acid
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type the numerical value of zincs melting point (in degrees celsius). (…
419.53
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which of these factors will cause a solid solute to dissolve faster? ○ …
D. increasing the surface area of solute
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type the numerical value of coppers melting point (in degrees celsius).…
1085
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which are produced when hcl reacts with ca(oh)₂? ○ cl₂, h₃, and cao ○ c…
D. $\ce{CaCl_{2}}$ and $\ce{H_{2}O}$ (assuming the last option is labeled D, with the correct formula $\ce{CaCl_{2}}$ and $\ce{H_{2}O}$)
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use the following table to answer the question. strong acids\tweak acid…
A. \( 2NaOH + H_2SO_4 \)
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an acid (x) reacts with a base (y) to produce mg₃(po₄)₂. what are x and…
B. \( X = \ce{H3PO4} \), \( Y = \ce{Mg(OH)2} \)
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there are two stanzas with the rhyme scheme abab throughout. there are …
The correct option is: "There are two stanzas with the rhyme scheme ABCB throughout." (Assuming the poem’s structure matches this; adjust if the poem’s actual scheme differs, but …
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use the following table to answer the question. | strong acids | weak a…
D. \( NaOH + CH_3COOH \)
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question 3 4 pts what hazardous properties does sodium hydroxide have? …
- $\boldsymbol{\text{Can release dangerous amount of heat when dissolved in water.}}$ (checked) - $\boldsymbol{\text{Can cause blindness if it contacts your eyes.}}$ (checked) - $…
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question 2 1 pts where is the hottest part of the bunsen burner flame? …
A. at the tip of the inner (bright blue) cone
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which equation represents the total ionic equation for the reaction of …
C. $\ce{H^{+} + NO^{-}_{3} + Na^{+} + OH^{-} -> Na^{+} + NO^{-}_{3} + H_{2}O}$
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question 1 match the following terms and definitions... a substance tha…
To solve this matching problem, we recall the definitions of key chemical terms: 1. **"A substance that has the characteristic properties of a metal and contains more than one ele…
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consider the incomplete reaction below. naoh + x —→ nach₃coo + h₂o what…
D. $\ce{CH3COOH}$
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which scientist developed the first model of the atom that proposed the…
D. Thomson
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what is the net ionic equation for the reaction that is represented by …
\( 2\mathrm{PO}_4^{3-} + 3\mathrm{Ca}^{2+} \longrightarrow \mathrm{Ca}_3(\mathrm{PO}_4)_2 \)
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which statement belongs to dalton’s atomic theory? atoms have a massive…
Atoms cannot be created or destroyed.
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conservation of mass in chemical reactions: investigating the rearrange…
### Fill in the Blank Answers: 1. The Law of **Conservation** of Mass says that mass is not created or destroyed in a chemical reaction. (From the text: "This is called the Law of…
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which statement best describes the ph of pure water? ∘ it is neutral be…
It is neutral because the concentration of hydronium ions equals that of hydroxide ions.
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element atomic number # of protons # of electrons # of valence electron…
| Element | Atomic Number | # of Protons | # of Electrons | # of Valence Electrons | Circle (GAIN/LOSE/NEITHER + electrons) | Oxidation Number | |---------|---------------|-------…
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scientists have changed the model of the atom as they have gathered new…
A. A few of the positive particles aimed at a gold foil seemed to bounce back.
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which would most likely be the ph of a highly-corrosive acid? ○ 1 ○ 5 ○…
A. 1
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the ph of a solution is 2.0. which statement is correct? useful formula…
A. The pOH of the solution is 12.0.
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the atomic models after dalton’s time included ideas about the atomic s…
Rutherford’s model
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3. sodium chloride can be made by reacting sodium metal with chlorine g…
- Sodium chloride is a substance. - Sodium chloride is a compound. - Sodium chloride is composed of two elements.
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which describes an alkaline solution? ○ ph less than 7 ○ ph equal to 7 …
C. basic
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the charged particles in the beams that thomson studied came from atoms…
C. An atom’s smaller negative particles are at a distance from the central positive particles, so the negative particles are easier to remove.
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a solution containing hcl would likely have ○ a high ph and a low poh. …
B. a low pH and a high pOH.
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1. which diagrams represent a compound? each color represents a differe…
The first (top - most) diagram (with blue and red touching circles) and the second diagram (with blue and white touching circles) represent compounds. If we consider the checkboxe…
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what is the ph of a solution with h⁺ = 1.25 × 10⁻¹⁰ m? use ph = -logh₃o…
9.90
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based on the definition of logarithms, what is the difference in hydrog…
A. A substance with a pH of 2 has a 10 times higher concentration of \( H^+ \) than a substance with a pH of 3.
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which statement about the self-ionization of water is correct? ○ two wa…
B. Two water molecules interact to form a hydronium ion and a hydroxide ion.
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heating curve 1. what is the melting point of the substance? 2. what is…
\( 60^\circ \text{C} \) ### Question 2: What is the boiling point of the substance?
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what is the equilibrium constant of pure water at 25°c? ○ 10¹⁴ ○ 10⁻¹⁴ …
B. \(10^{-14}\)
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consider the reaction below. h₂po₄⁻ + h₂o → h₃o⁺ + hpo₄²⁻ which of the …
A. $\ce{H_{2}O}$ and $\ce{H_{3}O^{+}}$
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which term describes a substance that increases the concentration of hy…
B. Arrhenius definition of a base
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osmium is a chemical element with a density of 22.6 grams per cubic cen…
D. 341.3 grams
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which of the following would most likely act as a bronsted-lowry acid? …
B. HCN
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consider the reaction below. hclo₃ + nh₃ → nh₄⁺ + clo₃⁻ which is a base…
B. $\ce{NH_{3}}$ and $\ce{NH_{4}^{+}}$
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what is the definition of a lewis acid? ○ a substance that accepts elec…
A. a substance that accepts electrons to form a covalent bond
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which statement best describes a bronsted-lowry base? it must accept pr…
B. It must accept protons to form a conjugate acid.
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consider the reaction below. hi + h₂o → h₃o⁺ + i⁻ which is an acid-conj…
D. HI and $\ce{I^-}$
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what is the arrhenius definition of an acid? a substance that increases…
A. A substance that increases $\ce{H_3O^+}$ concentration when it is dissolved in water.
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what is the bronsted-lowry definition of a base? ○ a compound that dona…
B. a compound that accepts protons
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1) draw an atom of helium, include the electrons, protons and neutrons.…
- Nucleus: 2 protons (labeled p⁺) and 2 neutrons (labeled n⁰). - Electron shell: 2 electrons (labeled e⁻ or "X") in the first shell. ### Question 2: Determine Helium’s oxidation/c…
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which reaction displays an example of an arrhenius base? ○ naoh(s) → na…
A. $\ce{NaOH(s) ightarrow Na^{+}(aq) + OH^{-}(aq)}$
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when does phenolphthalein turn pink? ○ in the presence of a base ○ in t…
A. in the presence of a base
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which of these substances contributes to soap’s slippery texture? ○ an …
B. a base
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which pair of substances would most likely result in the production of …
B. soluble metal salt and carbon dioxide
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which of the following best defines an acid? ○ an acid has a ph of 7. ○…
D. An acid has more hydrogen ions in solution.
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oxytocin also plays a role in sexual relationships. the so - called \lo…
A. It encourages us to form emotional bonds with others.
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the reaction below demonstrates which characteristic of a base? $ce{cus…
the ability of a base to react with a soluble metal salt
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h₂co₃ is used in soft drinks. what is the name of this compound? ○ sulf…
B. carbonic acid
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look at the reaction below. h₂so₄(aq) + ca(oh)₂(aq)→caso₄(aq) + 2h₂o(l)…
D. $\ce{Ca(OH)_{2}(aq)}$
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which statement would indicate the presence of an acid? ○ it tastes bit…
C. It reacts with active metals to form a gas.
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13 multiple choice 7 points in chemistry, logarithms are key to calcula…
\( H^+ \approx 2.5 \times 10^{-3} \) (corresponding to the first option: \( H^+ \approx 2.5 \times 10^{-3} \))
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which compound plays an important role in leather processing and electr…
ammonia
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4. how would you write the element symbol for this element? key concept…
1. Atomic number (number of protons) 2. No; neutrons affect mass, not identity (isotopes are same element). 3. No; electrons can vary (ions) without changing the element. 4. No; p…
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multiple-choice (record the best or most correct answer on the student …
To solve these multiple - choice questions, we analyze each one based on the knowledge about Alfred Nobel and nitroglycerin: ### Question 1 Nitroglycerin was first made by Ascanio…
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10 multiple answer 1 point why is methanol cooled before rinsing the cr…
C. Cold methanol prevents dissolution of the purified naphthalene, D. Cold methanol dissolves remaining impurities more effectively
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9 multiple choice 1 point when recrystallizing naphthalene, why is it i…
A. To remove any undissolved impurities
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8 multiple choice 1 point why is methanol handled in a fume hood during…
A. Methanol fumes are toxic and flammable.
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7 multiple choice 1 point after recrystallization, the purified sample …
B. Higher degree of purity
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6 multiple choice 1 point why is methanol initially chosen over water a…
C. Methanol has a lower polarity than water, enhancing naphthalene solubility at high temperatures. (Here we assume the options are labeled A, B, C, D in order. If the original la…
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5 multiple choice 1 point what is the expected solubility behavior of n…
C. Highly soluble in methanol at high temperature but poorly soluble in water at all temperatures
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4 multiple answer 1 point which property of a good recrystallization so…
B. High solubility of the compound at high temperature, D. Low boiling point to evaporate easily, A. Ability to dissolve impurities at all temperatures (Note: Actually, the most e…
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3 multiple choice 1 point what is the main reason for adding water drop…
B. To increase the polarity of the solvent mixture gradually, promoting controlled crystallization.
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2 multiple choice 1 point in mixed-solvent recrystallization, why must …
A. To avoid phase separation and allow uniform solubility adjustment
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pre-lab quiz 3. answer all questions 1 multiple choice 1 point which pa…
B. Hexane - methanol
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name: _______________________________ pd. ____ date: ______________ 5. …
| Symbol | Element Name | Atomic Mass | Atomic Number | Atomic Notation | Number of Protons | Number of Neutrons | Number of Electrons | |--------|--------------|-------------|---…
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which is a way to express concentration of a solution? ○ parts per bill…
A. parts per billion
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given that the molar mass of nano₃ is 85.00 g/mol, what mass of nano₃ i…
255 g
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practice problems 1. compare a molecule of oxygen (o₂) and a molecule o…
B) $CO_2$ ### Problem 3: Fill in the blank: An element is made of only one kind of ______.
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which would be the best way to represent the concentration of a 1.75 m …
B. $\boldsymbol{[K_2CrO_4] = 1.75\ M}$
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a student prepares 150.0 ml of 1.40 m hcl using 35.0 ml of a stock solu…
6.00 M
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1. label the diagram of the atom below using the provided word bank. pr…
1. a. Proton, b. Neutron, c. Electron, d. Electron Shell/Orbit 2. a. Electron, b. Proton, c. Electron Shell/Orbit, d. Neutron 3. a. The number of protons in an atom, b. The sum of…
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which statement best explains the symbol nacl? moles of water per liter…
C. moles of NaCl per liter of solution
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josh prepares a solution by mixing sodium nitrate and water. to calcula…
B. sodium nitrate, because it is the solute
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in a schools laboratory, students require 50.0 ml of 2.50 m h₂so₄ for a…
6.94 mL
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which solution is the most concentrated? ○ 2.0 ml of 10 m h₂so₄, where …
2.0 mL of 10.5 M $\ce{H_2O_2}$, where $\ce{H_2O_2}$ has a molar mass of 34 g/mol
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in a group assignment, students are required to fill 10 beakers with 0.…
200 g (Note: The precise calculation gives approximately 198 g, which is closest to 200 g among the options)
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a student takes a measured volume of 3.00 m hcl to prepare a 50.0 ml sa…
30.0 mL
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the concentration of a solute in a solution is greater than the maximum…
D. supersaturated
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1. t or f - all associates are responsible for working safely and repor…
T ### Question 2
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which factor increases the rate of dissolution in an unsaturated soluti…
A. increasing the temperature
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a 1-l soda bottle contains dissolved carbon dioxide gas. which bottle w…
a bottle that is sealed
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which is true about the dissolving process in water? ○ nonpolar solutes…
C. Molecules or ions of a solute spread throughout the water molecules.
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which is the second step in the dissolving process? ○ the solute is mix…
D. The solvent molecules are attracted to solute particles or ions.
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under which conditions would the solubility of a gas be greatest? ○ hig…
B. high pressure and low temperature