Which set of procedures and observations indicates a chemical change?(1) Ethanol is added to an empty beaker and the ethanol eventually disappears.
(2) A solid is gently heated in a crucible and the solid slowly turns to liquid.
(3) Large crystals are crushed with a mortar and pestle and become powder.
(4) A cool, shiny metal is added to water in a beaker and rapid bubbling occurs.
Answers
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What is 19 degrees Celsius in Fahrenheit?
A 1.0-gram piece of zinc reacts with 5 milliliters of HCl(aq). Which of these conditions of concentration and temperature would produce thegreatest rate of reaction?(1) 1.0 M HCl(aq) at 20.°C(2) 1.0 M HCl(aq) at at 40.°C(3) 2.0 M HCl(aq) at at 20.°C(4) 2.0 M HCl(aq) at at 40.°C
The chemical formula for emerald is Be3Al2(SiO3)6. An emerald can be described asa pure substance because it is a compound. a pure substance because it is an element. an impure substance because it is chemically combined. an impure substance because it is a mixture.
What is the mass of 1 mole of Na3,PO4?
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density = mass or volumes
It does't matter which mass do you have- density is always the same, therefore 13.6 g/cm^3×10
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33.6 liters* 1mol/22.4liters = 1.5 mols.
Molar mass of carbon dioxide: 12 g/mol + 2x16 g/mol = 44 g/mol
Mass of 1.5 mols = 1.5mol * 44 g/mol = 66 g.
the most energy to remove an
electron?
Why do these elements have a higher ionization energy?
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Answer:
Noble gases
Explanation:
The noble gases are non-metals that requires the highest amount of energy to remove an electron from their shells.
The reason for this difficult is that their electronic configuration confers a stable configuration them.
- The ionization energy is the energy required to remove the most loosely held electrons in an atom.
- Due to the special stability of noble gases, it is very difficult to remove electrons from an atom of noble gases.
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Answer:
The net charge of 1.3 g nugget of pure gold after 1.68% of its electrons are removed is 559 C
Explanation:
When an atom gains electrons it becomes negatively charged. Conversely, when it looses electrons the atoms becomes positively charged thus
To solve this question, we rely on the relationship between the nmber of particles present in a given mass of an atom, Avogadro's number and number of moles, n
The given variables are
mass of pure gold nugget = 1.30 g
Quantity of electrons removed = 1.68% of electrons present in the gold sample
Molar mass of gold = 197 g/mol
Avogadro's number = 6.02 × 10²³ atoms/mole
qc = one electron charge = -1.06 × 10⁻¹⁹ C/electron
Electrical charge of gold nugget = 0 C
Number of electrons in one gold atom = 79 electrons
Solving for the number of prticles or gold atoms in 1.3 grams of gold we get
n mass/(molar mass) = 1.3/197 moles of gold = 0.0066 moles
number of particles in 0.0066 moles of gold N = n× = 0.0066 × 6.02 × 10²³ = 3.97 × 10²¹ atoms
since 79 electrons are present per particle we have
3.97 × 10²¹ × 79 = 3.14 × 10²³ electrons
quantity of elecrtrons removed = 1.68% of 3.14 × 10²³ electrons =1.68/100 × 3.14 × 10²³ electrons = 0.0168 × 3.14 × 10²³ electrons = 5.3 × 10²¹ electrons
The net charge of 5.3 × 10²¹ electrons = 5.3 × 10²¹ electrons × -1.06 × 10⁻¹⁹ C/electron =
5.59 × 10² C = 559 C
B. The critical temperature is the temperature above which the liquid phase of a pure substance cannot exist.
C. The critical temperature is the temperature below which the liquid phase of a pure substance cannot exist.
D. The critical temperature is the temperature at which all three phases can coexist.
E. The critical temperature is the temperature at which the pure substance reaches, but cannot go beyond, the critical pressure.
Can someone explain this one?
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After temperature reaches certain treshold the difference between density of liquid and gas state disappears, and it is impossible to liquify the substance.
Answer:what do u mean tho
Explanation: