Chem101 Practice Problems

Can you do number 7 or 7 and 8

An analytical chemist measures the amount of Elements E₁ and E₂ in four samples of an unknown Substance. sample of E1 1 2 3 mass mass of E2 4 16.0 g 9.1 g 17.1 g 9.8 g 18.5 g 10.6 g 12.0 g 6.9 g It's known that X contains no elements other than E₁ and E₂. Using this information, answer the questions in the table below. Is X a pure substance or a mixture? If you don't have enough information to decide, choose can't decide. If you said X is a pure substance, calculate the mass of Element E₁ the analytical chemist would find in a new 10.0 g sample of X. Round your answer to 2 significant digits. O pure substance O mixture O (can't decide) g

4. Calculating Mass of an Element in a Compound. Pitchblende is the most important compound of uranium. Mass analysis of an 84.2-g sample of pitchblende shows that it contains 71.4 g of uranium, with oxygen the only other element. How many grams of uranium and of oxygen are in 102 kg of pitchblende?-

An oxygen atom has a mass of 2.6610−23g and a glass of water has a mass of 0.050kg. Use this information to answer the questions below. Be sure your answers have the correct number of significant digits. What is the mass of 1 mole of oxygen atoms? How many moles of oxygen atoms have a mass equal to the mass of a glass of water?

U-238 is naturally the most abundant form of uranium; however, only U-235 can be used as fuel in a nuclear reactor, so uranium for us in the nuclear industry must be enriched in this isotope. If a sample of enriched uranium has 78.72% of U-235 isotope and 21.28% U-238 isotope, what is the average atomic mass of the Uranium sample?

A nutrition table lists apples with a potassium content of 4600 mg/pound. Assume an average apple is 75.0 g, the minimum daily intake for potassium for a healthy adult is 3500. mg per day. Calculate the number of apples per day to meet this requirement for a healthy adult. Assume 454 g = 1 pound. O 7.96 apples per day O 0.126 apples per day O 0.217 apples per day O 4.61 apples per day

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An element, Spencerecium, has two isotopes.  Spencerecium-145 has a relative abundance of 85 % and Spencerecium-140 has a relative abundance of 15 %.  What is the average atomic mass of Spencerecium?  Include two decimal places in your answer.

Question 16 Which one of the following is a physical change? A. CH4(g) +202(g) → 2H₂O(g) + CO2(g) C. H2O(s)→ H₂O(1) Combustion of hydrogen Decomposition of NaN3 B. D. OA OB OD Which pair of elements would you expect to show the greatest similarity in their physical and chemical properties? A. O, S C. K, Ca B. C, N D. H, He OA OB OC OD Question 18 Which one of the following has the element name and symbol correctly matched? a) P, potassium b) C, copper c) Mg, manganese d) Ag, silver OA OB OC OD Moving to anouer que o Anions are formed when atoms a) gain protons Question 17 Question 19 OA OB OC OD b) lose neutrons c) gain electrons d) lose electrons

How many atoms are there in each of the following substances? I.) 5.14 g P Express your answer using three significant figures. II.) 2.36 g Hg Express your answer using three significant figures. III.) 1.92 g Bi Express your answer using three significant figures.   IV.) 8.4×10−2 g Sr Express your answer using two significant figures.

A tiny sample of gold contains  1.5 x 10^16 atoms.The mass of the gold sample is ______  μg.

A new (imaginary) element has been discovered.  It exists in three naturally occurring isotopic forms. ISOTOPE Mass (amu) Abundance (%) Isotope 1 300.696 17.872 Isotope 2 302.757 20.185 Isotope 3 305.735 61.943 Calculate the mass for the element as it would appear in the periodic table.  Report your answer to two decimal places.Answer

Determine the number of hydrogen atoms in one liter of water. The density of water is 1 g/ml.

Element X forms three different compounds with element Y. Information about these compounds is contained in the table. Mass of Y per Compound Formula gram of X 2.82 g 1 XY6 XY? 1.41 g 3 XY, 0.94 g What are the formulas of compounds 2 and 3? Replace each question mark with the appropriate integer. compound 2: ||XY. compound 3: ||XY2 ?3 Incorrect Incorrect

Please help complete question 3, 4 and 5

PART 1 Prelab Question = tr²l_ (I=length of wire) The density of copper at 20°C is 0.896 kg/dL at 20°C. A copper wire has a diameter of 0.110 mm. If the copper wire consists of 1.61376 x 1021 atoms of copper, calculate the length of the copper wire.

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6. Milk of lime is lime in water. true or false

Classify each statement as an observation, a law, or a theory. If elements are listed in order of increasing mass of their atoms, their chemical reactivity follows a repeating pattern.

Determine the mass of tin that contains 6.89×10^18 tin atom

Please help with this question in this format

Write the letter of the correct answer (one letter per number)

true or false

Use the data below to determine the mass ratio of iron to oxygen for compound 2.

Al:CuCl2 ratio Mass of Al (g) Calculated mass of CuCl2 (g) 1:1 mass ratio 0.250   2:1 mass ratio 0.250   2:3 mass ratio 0.250

Differentiate between Molecules and Molecular Compounds?

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An unknown element (Uk) has three isotopes, seen in the table. One of the percentage values is missing. Percent Isotope Notation Mass (amu) Abundance (%) Uk-66 65.994 57.00 Uk-69 68.958 13.00 Uk-71 70.975 ? Once you have found the missing percentage, calculate the average atomic mass of Uk. Enter your answer to the hundredths place.

59 Experiment 7 Chemical Properties of Compounds: Chemical Reactions Date: Name: Experiment 7 Chemical Properties of Compounds: Chemical Reactions Questions and Problems (May be assigned before or after the experiment, depending on your instructor.) (Show all calculations where appropriate.) toom temperature white solid is mixed with a room temperature clear liquid resulting in a clear, colorless quid that is hot to the touch. Has a chemical reaction occurred? Why or why not? (It may be possible to argue in favor of yes OR no. Defend YOUR answer. Introduction 2. A clear, colorless liquid is mixed with a clear, blue liquid resulting in a white powder suspended in a clear, colorless liquid. Has a chemical reaction occurred? Why or why not?

be sure your answer is correct and have the correct number of significant digits

Od. 1.03 x 10-27 QUESTION 3 The number of neutrons, protons, and electrons in A7A9 are 108 47 Oa. p = 47, n= 108, e = 61 %3D b. p = 47, n= 61, e = 47 C. p = 47, n= 108, e = 47 Od.p = 61, n= 47, e = 61 QUESTION 4 106.