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13 Dec 2019

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In a flame test:

1. Boron burns green/blue and Arsenic burns deep blue, Molybdenum burns yellow/green, and Rubidium burns red. Which light has the most energy in it? Which has the least?

2. Magnesium and Berilyium have similar flame test results, but Calcium has a very different flame. What's different about the available orbitals for Calcium that could account for this?

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Patrina SchowalterLv2

16 Dec 2019

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Magnesium and Beryllium have similar flame test results, but Calcium has a very different flame. Whatâs different about the available orbitals for Calcium that could account for this?

provided to determine AH rxn for the following reaction: urf (klimol) CH4(g) + 3 Cl2(g) â CHCI3() + 3 HCI(g) airrxn-? A)-151 kJ B)33SkJ C) +662kJ D) +117kJ E)-217 kJ A) 4.1 atm B) 5.0 atm c) 6.4 atm D)1.1 atm E) 2.3 atm kg) of the copper sample if the specific heat capacity of copper is 0 CH4(g) 75 CHCI3() -134 HCI(g) -92 8) What pressure will 14.0 g of CO exert in a 3.5 L container at 75 C? 9) A sample of copper absorbs 43.6 kJ of heat, resulting in a temperature rise of 50.0Â°C, determine the mass (in .385 J/g C A) 226 kg B) 0.235 kg C)6.64 kg D) 119kg E)5.10 kg 10) Which of the following processes is exothermic? A) the ionization of a melting snow atom B) the breaking of a boiling of water bond C) the boiling of water D) the condensation of water E) All of the above processes are exothermic 11) Calculate the energy of the red light emitted by a neon atom with a wavelength of 703.2 nm. B)4.27 x 10-19J C) 2.34 x 10-19J D)6.45 x 10-19J E) 2.83 x 10-19J A)3.54 Ã 10-19J 12) Identify the color of a flame test for potassium D) yellow A) violet B) red C) white E) blue 13) Which of the following statements is TRUE? A) The emission spectrum of a particular element is always the same and can be used to identify the element. B) Part of the Bohr model proposed that electrons in the hydrogen atom are located in "stationary states" or particular orbits around the nucleus. C) The uncertainty principle states that we can never know both the exact location and speed of an electron. D) An orbital is the volume in which we are most likely to find an electron. E) All of the above are true. 14) Calculate the wavelength of an electron (m-9.11 x 10-28 g) moving at 3.66 Ã 106 m/s. A)1.99 x 10-10m B)5.03 x 10-10 m C) 1.81Ã10-10 m D)5.52 Ã 10-9 m E) 2.76 Ã 10-9 m 15) Which of the following quantum numbers describes the shape of an orbital? A) principal quantum number B) magnetic quantum number C) spin quantum number D) SchrÃ¶dinger quantum number E) angular momentum quantum number 16) Determine the energy change associated with the transition from n = 2 to n-5 in the hydrogen atom. A)-218Ã10-19J B)+654 Ã 10-19 J C) +4.58 x 10-19 J D)-1.53 x 10-19 J E) +3.76 Ã 10-19J 17) If two electrons in the same atom have the same value of I, they are A) in the same sublevel, but not necessarily in the same level. me level, but different sublevel. C) in the same orbital. D) in different levels and in different shaped orbitals. E) none of the above.

Decomposition of Malachite

Here is what Malachite is Made Out Of

Malachite is a famous and very popular semi-precious stone. Its banded light and dark green bands are one-of-a-kind, and give it a unique ornamental quality unlike that of any other stone. The light and dark green bands are so distinctive that malachite may be one of the most easily recognized minerals by the general public. Malachite is popular in jewelry, especially Native American southwestern jewelry. The stones inlayed in silver make a nice alternative to traditional turquoise jewelry.

Malachite is a form of copper carbonate with the molecular formula Cu₂CO₃(OH)₂. When heated to around 200 ï¿½C, malachite decomposes into copper (II) oxide (CuO) and other products.

Reaction Stoichiometry

The Law of Conservation of Mass states that matter can neither be created nor destroyed. Therefore, the number of atoms of each element on the reactants side must be same as the number of atoms on the products side. This quantitative study of chemical reactions is called stoichiometry. The substances in a balanced reaction are related to each other by stoichiometric molar ratios. For example, magnesium reacts with hydrochloric acid in a 1:2 stoichiometric ratio in the balanced equation below.

Mg(s) + 2HCl(aq) -> MgCl2(aq) + H2(g)

The molar ratios can be used as conversion factors to find the amount (in moles) of one substance given the amount of another. For example, given the number of moles of HCl, the amount of MgCl₂ can be determined as shown below.

nMgCl2=nHCl x (1mol MgCl2) / (2mol HCL)

The molar ratios are used to determine the amount in moles. However, the amount of reactant or product is often measured in grams. Mass can be converted to moles and vice versa as shown below.

n = m / (MM)

m = n x MM

where n is the number of moles, m is the mass of the product in g, and MM is its molar mass in g/mol.

To observe the Law of Conservation of Mass, you can perform different types of chemical reactions. For example, you can use a decomposition reaction to observe one compound being broken down into two or more elements or new compounds. For this reaction to take place, you must break existing bonds within the starting compound. Different sources of energy such as heat, light, or electricity may be used. Through a decomposition reaction, you can observe that the atoms in the original compound are not destroyed but are rearranged to form simpler substances, such as elements or compounds.

About This Lab

In this lab, you will test if the relationship between malachite and copper (II) oxide is stoichiometric. To do this, you will heat a known mass of malachite to produce copper (II) oxide. You will then compare the amount of copper (II) oxide obtained experimentally with the amount of copper (II) oxide expected from the balanced equation for the decomposition reaction.

1.Take a crucible from the Containers shelf and place it on the workbench.

2.Take a balance from the Instruments shelf and place it on the workbench.

3.Move the crucible onto the balance. Record the mass of the empty crucible to the nearest 0.001g in your Lab Notes.

4.Move the crucible onto the workbench.

5.Take copper (II) carbonate hydroxide from the Materials shelf and add 10 g to the crucible.

6.Move the crucible onto the balance and record the mass of the crucible containing copper (II) carbonate hydroxide in your Lab Notes.

7.Take a Bunsen burner from the Instruments shelf and place it on the workbench.

8.Move the crucible onto the Bunsen burner.

9.Double-click on the crucible to open its properties. Select Show Contents and click OK. This gives you a cut-away view of the crucible's contents.

10.Turn the Bunsen burner on to low flame by clicking the knob at the bottom once. Clicking multiple times will increase the intensity of the flame until it is turned off.

11.Watch the crucible until the malachite fully decomposes. You will see a distinct color change.

12.Move the crucible onto the workbench to cool.

13.Turn off your Bunsen burner.

14.Weigh the crucible with its contents and record the mass to the nearest 0.001 g in your Lab Notes.

Clear your station.

Lab Notes:

Numbers below refer to numbers in the above âAbout this Labâ

3. Empty crucible = 88 g

5. Added 10 g of Copper (II) carbonate hydroxide to crucible

6. Crucible with Copper (II) carbonate hydroxide = 98 g

11. to Black

14. after heating crucible with its contents = 95.195

Questions I have answered:

How many grams of malachite did you add to the crucible? 10g

How many grams of product were in the crucible after heating? 7.195

By how much did the mass of the crucible's contents change after heating? -2.805

The molar mass of malachite is 221.1 g/mol. How many moles of malachite were present before the reaction? 0.04523 mol

The product remaining in the crucible after heating is copper (II) oxide. The molar mass of copper (II) oxide is 79.55 g/mol. How many moles of copper (II) oxide were produced during the reaction?

0.0945 mol

Please answer the following:

Q1 a. Which of the following represents the balanced chemical equation for this reaction?

Cu2CO3(OH)2=2CuO+H2O

Cu2CO3(OH)2=CuO+CO2

Cu2CO3(OH)2=2CuO+H2O+CO2

Cu2CO3(OH)2=CuO+H2O+CO2

b. Based on the number of moles of malachite that you started with, how many grams of water were produced? The molar mass of water is 18.0153 g/mol. Choose the closest answer.

1.815 g 0.8148 g 1.630 g 1.982 g

c. Based on the number of moles of malachite that you started with, how many moles of CO₂were produced? Choose the closest answer.

1.000 mol 0.04523 mol 0.9000 mol 0.09045 mol

d. Based on the number of moles of malachite that you started with, how many grams of CO₂were produced? The molar mass of CO₂ is 44.01 g/mol. Choose the closest answer.

1.991 g 0.4401 g 0.04523 g 3.981 g

Q2a. Based on the number of grams of CO₂ and H₂O produced during the reaction, does this compensate for the observed loss of mass?

A. No, because this violates the law of conservation of mass

B. yes, this compensates for the mass lost in the reaction

C. No, because more copper oxide was produced

D. No because mass is conserved

b. You observed that the products in the crucible weigh less than the reactants that you added. How is this possible?

A. Mass was lost due to experimental error

B. The Malachite absorbed CO2 from the air

C. CO2 and H2O were released as gases

D. Mass was converted to energy

c. What kind of a reaction took place upon heating?

A. decomposition

B. single displacement

C. synthesis

D. Double displacement

d. Baking soda is used as a leavening agent in baking. When heated, baking soda undergoes a decomposition reaction to form carbon dioxide. Given the data below, which of the following reactions occurs during baking? The molar mass of baking soda is 84.007 g/mol and the molar mass of carbon dioxide is 44.01 g/mol.

Mass of empty crucible (g) = 55.000

mass of crucible with baking soda (g) = 57.000

mass of crucible and contents after the reaction (g) =56.260

A. 2NaHCO3= 2Na+2CO2 +H2O

B. 2NaHCO3 = Na2O + 2CO2 +H2O

C. NaHCO3 = NaOH +CO2

D. 2NaHCO3 = Na2CO3 + CO2 +H2O

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