Mass Hysteria!
State the law of conservation of mass.
What is matter cannot be created or destroyed in an ordinary chemical reaction?
Is aluminum a metal or nonmetal?
what is Metal
What two general types of elements usually combine to form an ionic compound?
what is A metal and a nonmetal.
Name CO₂.
Carbon dioxide.
How many total atoms are in C₂H₆?
8 atoms.
A 70.0 g substance decomposes into 18.0 g of ash, 22.0 g of water, and a gas. How much gas forms?
What is 30.0 g
What is a pure substance?
what is Matter consisting of only one kind of element or compound, with a fixed composition.
Which type of compound uses prefixes such as mono-, di-, and tri-?
what is Covalent (molecular) compounds.
Name N₂O₅.
Dinitrogen pentoxide.
How many total atoms are in C₆H₁₂O₆?
24 atoms.
Which law states that a particular compound always contains the same elements in the same mass proportions?
What is Law of definite proportions
Classify saltwater: pure substance, homogeneous mixture, or heterogeneous mixture?
what is Homogeneous mixture, assuming the salt is completely dissolved.
Which would typically conduct electricity in water: dissolved KCl or dissolved sugar? Why?
KCl, because it produces mobile ions in solution.
Name Mg₃N₂.
Magnesium nitride.
A molecule contains 19 atoms and has formula C₄H₁₀Clₓ. Find x.
x = 5.
Name the four main assumptions of Dalton's atomic theory.
What is Matter consists of atoms; atoms of the same element are identical in Dalton's model; atoms of different elements differ; compounds form in simple whole-number ratios and chemical reactions rearrange atoms.
Classify each: oxygen gas, pure water, muddy water, and brass.
what is Oxygen: element; pure water: compound; muddy water: heterogeneous mixture; brass: homogeneous mixture (alloy).
Classify MgO, CO₂, NaCl, and PCl₃ as ionic or covalent.
MgO and NaCl: ionic. CO₂ and PCl₃: covalent.
Write the chemical formula for sulfur hexafluoride.
SF₆.
A compound contains 12 g carbon for every 32 g oxygen. How much oxygen is needed to combine with 30 g carbon?
80 g oxygen. Set up 32/12 = x/30.
Compound A contains 14 g nitrogen and 16 g oxygen. Compound B contains 21 g nitrogen and 24 g oxygen. Do these data establish two different compounds? Explain.
What is No. Both have the same nitrogen-to-oxygen mass ratio, 7:8. The data are consistent with the same compound and do not demonstrate multiple proportions.
A clear liquid appears uniform. Explain why appearance alone cannot prove it is a pure substance, and describe a way to investigate.
what is A homogeneous mixture can look uniform. Evaporation or distillation may reveal separate components; a consistent boiling point under controlled conditions can also provide evidence of purity.
A solid dissolves in water. The solution does not conduct electricity. Is the compound more likely ionic or covalent? Explain and identify a limitation of this test.
More likely covalent because it does not produce enough mobile ions to conduct. Conductivity is evidence, not absolute proof; some ionic compounds have low solubility.
Name P₄O₁₀ and CaCl₂, then explain why one name uses prefixes and the other does not.
Tetraphosphorus decoxide and calcium chloride. P₄O₁₀ is covalent; CaCl₂ is ionic.
A compound contains 18 g of element A for every 24 g of element B. If 63 g of A reacts completely, how many grams of B are needed, and what total mass of compound forms?
84 g B; 147 g compound. Scale by 63/18 = 3.5, then apply conservation of mass.