Science Flashcards
(12 cards)
Select ALL the compounds listed below.
AgBr
ZnO
S
Au
K2Se
Fe
I2
AgBr
ZnO
K2Se
I
Serotonin is a chemical substance that acts as a neurotransmitter. It helps relay messages in the human brain. The formula for one molecule of serotonin is shown below.
C₁₀H₁₂N₂O
25
Carbon (C): 10 atoms
Hydrogen (H): 12 atoms
Nitrogen (N): 2 atoms
Oxygen (O): 1 atom
**
What is a precipitate?
* a solid substance that is formed during a chemical change when two or more liquids react
* a type of odor produced during a chemical change
* an odorless gas produced during a chemical reaction.
** a solid substance that is formed during a chemical change when two or more liquids react**
A chemist is performing a chemical reaction using potassium and chlorine. When these two chemicals are combined, a salt known as potassium chloride is formed. The equation of the reaction is shown below.
2K + Cl₂ → 2KCl
Which best describes how the reaction is an example of the law of conservation of mass?
The product has twice as many chlorine atoms as the reactants but has the same number of potassium atoms.
The product has twice as many potassium and chlorine atoms as the reactants.
The product has the same number of potassium atoms and chlorine atoms as the reactants.
The product has the same number of potassium atoms and the same number of chlorine atoms as the reactants.
**The product has the same number of potassium atoms and chlorine atoms as the reactants. **
Which of the following describes a physical change?
a change in the state of matter
a new gas or odor is produced
a new substance is formed
a precipitate is formed
a change in the state of matter
Which of the following does NOT indicate that a chemical reaction occurred when the iron filings were added to the Copper (II) Sulfate?
the total mass increased
the color of the solution changed
the temperature increased
the final solution formed bubbles
the final solution formed bubbles.
the total mass increased
A scientist spilled a few drops of dilute hydrochloric acid (HCl) on a lab table. For safety purposes, the scientist sprinkled some baking soda (NaHCO₃) onto the spill. Which observation would provide the best evidence that a chemical reaction occurred?
some of the baking soda dissolved in the hydrochloric acid
the baking soda and hydrochloric acid combined, and bubbles formed
the hydrochloric acid evaporated, leaving only the baking soda
the baking soda absorbed the hydrochloric acid
The baking soda and hydrochloric acid combined, and bubbles formed
How many different elements are involved in the chemical equation shown below?
SnO₂ + 2H₂ → Sn + 2H₂O
Tin (Sn)
Oxygen (O)
Hydrogen (H)
here are** 3 different elements i**nvolved in this chemical equation.
A balanced chemical equation is shown below use the equations to answer this question
2H2O+O2 → 2H2O2
How many atoms of Oxygen (O) are represented in the reactants?
2+2= 4 atoms of oxygen
All the following reactions are correctly balanced EXCEPT —
3NaHCO₃ + C₆H₈O₇ + H₂O → C₆H₅Na₃O₇ + 3CO₂ + 4H₂O
NaHCO₃ + CH₃COOH → CH₃COONa + H₂O + CO₂
2HCl + CuSO₄ → H₂SO₄ + CuCl₂
2NaOH + NaHSO₃ → Na₂SO₃ + H₂O
NaHCO₃ + CH₃COOH → CH₃COONa + H₂O + CO₂
Below is the chemical formula for sulfuric acid. Based on the chemical formula shown, how many molecules of sulfuric acid are present?
3H₂SO₄
3 molecules
Two solutions are mixed and react to produce the solid precipitate AgCl. The chemical reaction is shown by the balanced chemical equation.
AgNO3 + NaCl → AgCl + NaNO3
What happens to the total mass as the reaction takes place?
the mass decreases
the mass remains constant
the mass increases
the mass first decreases and then increases
the mass remains constant
