Tag Archives: Chemistry

Conceptual chemistry quiz

[qwiz]

[h] Chemistry concepts

[i] The 22 questions in this quiz are usually given to first-year college students beginning a general Chemistry class.  It measures their understanding of general Chemistry concepts.  Students taking this test averaged only about 45% correct.  When you understand why the right answers to these questions are the right answers you have excellent Chemistry knowledge!

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[q] Which of the following must be the same before and after a chemical reaction?
[c]IGEuIFRoZSBzdW0gb2YgdGhlIG1hc3NlcyBvZiBhbGwgc3Vic3RhbmNlcyBpbnZvbHZlZC48YnIgLz4K[c]IGIuIFRoZSBudW1iZXIgb2YgbW9sZWN1bGVzIG9mIGFsbCBzdWJzdGFuY2VzIGludm9sdmVkLjxiciAvPgo=[c]IGMuIFRoZSBudW1iZXIgb2YgYXRvbXMgb2YgZWFjaCB0eXBlIGludm9sdmVkLjxiciAvPgo=[c]IGQuIEJvdGggKGEpIGFuZCAoYykgbX VzdCBiZSB0aGUgc2FtZS48YnIgLz4K[c]IGUuIChlKSBFYWNoIG9mIHRoZSBhbnN3ZXJzIChhKSwgKGIpLCBhbmQgKGMpIG11c3QgYmUgdGhlIHNhbWUuPC9wPgo8cD5bISEhXSAmIzgyMTI7JiM4MjEyOyYjODIxMjsmIzgyMTI7JiM4MjEyOyAyICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjstIFsvISEhXTxiciAvPgo=[q] Assume a beaker of pure water has been boiling for 30 minutes. What is in the bubbles in the boiling water?
[c]IGEuIEFpci48YnIgLz4K[c]IGIuIE94eWdlbiBnYXMgYW5kIGh5ZHJvZ2VuIGdhcy48YnIgLz4K[c]IGMuIE94eWdlbi48YnIgLz4K[c]IGQuIFdhdGVyIHZh cG9yLjxiciAvPgo=[c]IGUuIEhlYXQuPC9wPgo8cD5bISEhXSAmIzgyMTI7JiM4MjEyOyYjODIxMjsmIzgyMTI7JiM4MjEyOyAzICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjstIFsvISEhXTxiciAvPgo=[q] A glass of cold milk sometimes forms a coat of water on the outside of the glass (Often referred to as ‘sweat’). How does most of the water get there?
[c]IGEuIFdhdGVyIGV2YXBvcmF0ZXMgZnJvbSB0aGUgbWlsayBhbmQgY29uZGVuc2VzIG9uIHRoZSBvdXRzaWRlIG9mIHRoZSBnbGFzcy48YnIgLz4K[c]IGIuIFRoZSBnbGFzcyBhY3RzIGxpa2UgYSBzZW1pLXBlcm1lYWJsZSBtZW1icmFuZSBhbmQgYWxsb3dzIHRoZSB3YXRlciB0byBwYXNzLCBidXQgbm90IHRoZSBtaWxrLjxiciAvPgo=[c]IGMuIFdhdGVyIHZhcG9yIGNvbmRlbnNl cyBmcm9tIHRoZSBhaXIuPGJyIC8+Cg==[c]IGQuIFRoZSBjb2xkbmVzcyBjYXVzZXMgb3h5Z2VuIGFuZCBoeWRyb2dlbiBmcm9tIHRoZSBhaXIgY29tYmluZSBvbiB0aGUgZ2xhc3MgZm9ybWluZyB3YXRlci48L3A+CjxwPlshISFdICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjsmIzgyMTI7IDQgJiM4MjEyOyYjODIxMjsmIzgyMTI7JiM4MjEyOy0gWy8hISFdPGJyIC8+Cg==[q] What is the mass of the solution when 1 pound of salt is dissolved in 20 pounds of water?
[c]IGEuIDE5IFBvdW5kcy48YnIgLz4K[c]IGIuIDIwIFBvdW5kcy48YnIgLz4K[c]IGMuIEJldHdlZW4gMjAgYW5kIDIxIHBvdW5kcy48YnIgLz4K[c]IGQuIDIxIHBvdW 5kcy48YnIgLz4K[c]IGUuIE1vcmUgdGhhbiAyMSBwb3VuZHMuPC9wPgo8cD5bISEhXSAmIzgyMTI7JiM4MjEyOyYjODIxMjsmIzgyMTI7JiM4MjEyOyA1ICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjstIFsvISEhXTxiciAvPgo=[q] The diagram represents a mixture of S atoms and O2 molecules in a closed container.

Which diagram shows the results after the mixture reacts as completely as possible according to the equation:

2S + 3O2 → 2SO3

[c]IGEuwqA=[c]IGIuwqA=[c]IGMuwqA=[c]IGQu IA==[c]IGUuPC9wPgo8cD5bISEhXSAmIzgyMTI7JiM4MjEyOyYjODIxMjsmIzgyMTI7JiM4MjEyOyA2ICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjstIFsvISEhXTxiciAvPgo=[q] The circle on the left shows a magnified view of a very small portion of liquid water in a closed container.

What would the magnified view show after the water evaporates?

[c]IGEuwqA=[c]IGIuwqA=[c]IGMuwqA=[c]IGQuIA==[c]IGUuPGJyIC8+ClshISFdICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjsmIzgyMT I7IDcgJiM4MjEyOyYjODIxMjsmIzgyMTI7JiM4MjEyOy0gWy8hISFdPGJyIC8+Cg==[q] True or False: When a match burns, some matter is destroyed.
[c]IGEuIFRydWU8YnIgLz4K[c]IGIuIEZhbHNlPC9wPgo8cD5bISEhXSAmIzgyMTI7JiM4MjEyOyYjODIxMjsmIzgyMTI7Ji M4MjEyOyA4ICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjstIFsvISEhXTxiciAvPgo=[q] What is the reason for your answer to the previous question? (True or False: When a match burns, some matter is destroyed.)
[c]IGEuIFRoaXMgY2hlbWljYWwgcmVhY3Rpb24gZGVzdHJveXMgbWF0dGVyLjxiciAvPgo=[c]IGIuIE1hdHRlciBpcyBjb25zdW1lZCBieSB0aGUgZmxhbWUuPGJyIC8+Cg==[c]IGMuIFRoZSBtYXNzIG9mIGFzaCBpcyBsZXNzIHRoYW4gdGhlIG1hdGNoIGl0IGNhbWUgZnJvbS48YnIgLz4K[c]IGQuIFRoZSBhdG9tcyBhcmUgbm90IGRlc3Ryb3llZCwg dGhleSBhcmUgb25seSByZWFycmFuZ2VkLjxiciAvPgo=[c]IGUuIFRoZSBtYXRjaCB3ZWlnaHMgbGVzcyBhZnRlciBidXJuaW5nLjxiciAvPgpbISEhXSAmIzgyMTI7JiM4MjEyOyYjODIxMjsmIzgyMTI7JiM4MjEyOyA5ICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjstIFsvISEhXTxiciAvPgo=[q] Heat is given off when hydrogen burns in air according to the equation

2H2 + O2 → 2H2O

Which of the following is responsible for the heat?
[c]IGEuIEJyZWFraW5nIGh5ZHJvZ2VuIGJvbmRzIGdpdmVzIG9mZiBlbmVyZ3kuPGJyIC8+Cg==[c]IGIuIEJyZWFraW5nIG94eWdlbiBib25kcyBnaXZlcyBvZmYgZW5lcmd5LjxiciAvPgo=[c]IGMuIEZvcm1pbmcgaHlkcm9nZW4tb3h5Z2VuIGJv bmRzIGdpdmVzIG9mZiBlbmVyZ3kuPGJyIC8+Cg==[c]IGQuIEJvdGggKGEpIGFuZCAoYikgYXJlIHJlc3BvbnNpYmxlLjxiciAvPgo=[c]IGUuIChhKSwgKGIpLCBhbmQgKGMpIGFyZSByZXNwb25zaWJsZS48YnIgLz4KWyEhIV0gJiM4MjEyOyYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjsgMTAgJiM4MjEyOyYjODIxMjsmIzgyMTI7JiM4MjEyOy0gWy8hISFdPGJyIC8+Cg==[q] Two ice cubes are floating in water:

After the ice melts, will the water level be:
[c]IGEuIGhpZ2hlcj88YnIgLz4K[c]IGIuIGxvd2VyPzxiciAvPgo=[c]IGMuIHRoZSBzYW1lPzxiciAvPgpbISEhXSAmIzgyMTI7JiM4MjEyOyYjODIxMjsmIzgyMTI7 JiM4MjEyOyAxMSAmIzgyMTI7JiM4MjEyOyYjODIxMjsmIzgyMTI7LSBbLyEhIV08YnIgLz4K[q] What is the reason for your answer to the previous question?
(Two ice cubes are floating in water. After the ice melts, will the water level be…)
[c]IGEuIFRoZSB3ZWlnaHQgb2YgdGhlIHdhdGVyIGRpc3BsYWNlZCBpcy BlcXVhbCB0byB0aGUgd2VpZ2h0IG9mIHRoZSBpY2UuPGJyIC8+Cg==[c]IGIuIFdhdGVyIGlzIG1vcmUgZGVuc2UgaW4gaXRzIHNvbGlkIGZvcm0gKGljZSkuPGJyIC8+Cg==[c]IGMuIFdhdGVyIG1vbGVjdWxlcyBkaXNwbGFjZSBtb3JlIHZvbHVtZSB0aGFuIGljZSBtb2xlY3VsZXMuPGJyIC8+Cg==[c]IGQuIFRoZSB3YXRlciBmcm9tIHRoZSBpY2UgbWVsdGluZyBjaGFuZ2VzIHRoZSB3YXRlciBsZXZlbC48YnIgLz4K[c]IGUuIFdoZW4gaWNlIG1lbHRzLCBpdHMgbW9sZWN1bGVzIGV4cGFuZC48L3A+CjxwPlshISFdICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjsmIzgyMTI7IDEyICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjstIFsvISEhXTxiciAvPgo=[q] A 1.0-gram sample of solid iodine is placed in a tube and the tube is sealed after all of the air is removed. The tube and the solid iodine together weigh 27.0 grams.

The tube is then heated until all of the iodine evaporates and the tube is filled with iodine gas. Will the weight after heating be:
[c]IGEuIGxlc3MgdGhhbiAyNi4wIGdyYW1zLjxiciAvPgo=[c]IGIuIDI2LjAgZ3JhbXMuPGJyIC8+Cg==[c]IGMuIDI3LjAgZ3Jh bXMuPGJyIC8+Cg==[c]IGQuIDI4LjAgZ3JhbXMuPGJyIC8+Cg==[c]IGUuIG1vcmUgdGhhbiAyOC4wIGdyYW1zLjwvcD4KPHA+WyEhIV0gJiM4MjEyOyYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjsgMTMgJiM4MjEyOyYjODIxMjsmIzgyMTI7JiM4MjEyOy0gWy8hISFdPGJyIC8+Cg==[q] What is the reason for your answer to the previous question?

(A 1.0-gram sample of solid iodine is placed in a tube and the tube is sealed after all of the air is removed. The tube and the solid iodine together weigh 27.0 grams.

The tube is then heated until all of the iodine evaporates and the tube is filled with iodine gas. The weight after heating is…)
[c]IGEuIEEgZ2FzIHdlaWdocyBsZXNzIHRoYW4gYSBzb2xpZC7ii4U8YnIgLz4K[c]IGIuIE1hc3MgaXMgY29u c2VydmVkLjxiciAvPgo=[c]IGMuIElvZGluZSBnYXMgaXMgbGVzcyBkZW5zZSB0aGFuIHNvbGlkIGlvZGluZS48YnIgLz4K[c]IGQuIEdhc2VzIHJpc2UuPGJyIC8+Cg==[c]IGUuIElvZGluZSBnYXMgaXMgbGlnaHRlciB0aGFuIGFpci48L3A+CjxwPlshISFdICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjsmIzgyMTI7IDE0ICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjstIFsvISEhXTxiciAvPgo=[q] What is the approximate number of carbon atoms it would take placed next to each other to make a line that would cross this dot? ⋅
[c]IGEuIDQ8YnIgLz4K[c]IGIuIDIwMDxiciAvPgo=[c]IGMuIDMwLDAwMC wwMDA8YnIgLz4K[c]IGQuIDYuMDIgeCAxMDxzdXA+MjM8L3N1cD48L3A+CjxwPlshISFdICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjsmIzgyMTI7IDE1ICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjstIFsvISEhXTxiciAvPgo=[q] Figure 1 represents a 1.0 L solution of sugar dissolved in water. The dots in the magnification circle represent the sugar molecules. In order to simplify the diagram, the water molecules have not been shown.

Which response represents the view after 1.0 L of water was added (Figure 2).

[c]IGEuwqA=[c]IGIu wqA=[c]IGMuwqA=[c]IGQuIA==[c]IGUuPC9wPgo8cD4mbmJzcDs8L3A+CjxwPlshISFdICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjsmIzgyMTI7IDE2ICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjstIFsvISEhXTxiciAvPgo=[q] 100 mL of water at 25°C and 100 mL of alcohol at 25°C are both heated at the same rate under identical conditions. After 3 minutes the temperature of the alcohol is 50°C. Two minutes later the temperature of the water is 50°C. Which liquid received more heat as it warmed to 50°C?
[c]IGEuIFRoZSB3YX Rlci48YnIgLz4K[c]IGIuIFRoZSBhbGNvaG9sLjxiciAvPgo=[c]IGMuIEJvdGggcmVjZWl2ZWQgdGhlIHNhbWUgYW1vdW50IG9mIGhlYXQuPGJyIC8+Cg==[c]IGQuIEl0IGlzIGltcG9zc2libGUgdG8gdGVsbCBmcm9tIHRoZSBpbmZvcm1hdGlvbiBnaXZlbi48L3A+CjxwPlshISFdICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjsmIzgyMTI7IDE3ICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjstIFsvISEhXTxiciAvPgo=[q] What is the reason for your answer to the previous question?
(100 mL of water at 25°C and 100 mL of alcohol at 25°C are both heated at the same rate under identical conditions. After 3 minutes the temperature of the alcohol is 50°C. Two minutes later the temperature of the water is 50°C. Which liquid received more heat as it warmed to 50°C?)
[c]IGEuIFdhdGVyIGhhcyBhIGhpZ2hlciBib2lsaW5nIHBvaW50IHRoZW4gdGhlIGFsY29ob2wuPGJyIC8+Cg==[c]IGIuIFdhdGVyIHRha2VzIGxvbmdlciB0byBjaGFuZ2UgaXRzIH RlbXBlcmF0dXJlIHRoYW4gdGhlIGFsY29ob2wuPGJyIC8+Cg==[c]IGMuIEJvdGggaW5jcmVhc2VkIHRoZWlyIHRlbXBlcmF0dXJlcyAyNcKwQy48YnIgLz4K[c]IGQuIEFsY29ob2wgaGFzIGEgbG93ZXIgZGVuc2l0eSBhbmQgdmFwb3IgcHJlc3N1cmUuPGJyIC8+Cg==[c]IGUuIEFsY29ob2wgaGFzIGEgaGlnaGVyIHNwZWNpZmljIGhlYXQgc28gaXQgaGVhdHMgZmFzdGVyLjwvcD4KPHA+WyEhIV0gJiM4MjEyOyYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjsgMTggJiM4MjEyOyYjODIxMjsmIzgyMTI7JiM4MjEyOy0gWy8hISFdPGJyIC8+Cg==[q] Iron combines with oxygen and water from the air to form rust. If an iron nail were allowed to rust completely, one should find that the rust weighs:
[c]IGEuIGxlc3MgdGhhbiB0aGUgbmFpbCBpdCBjYW1lIGZyb20uPGJyIC8+Cg==[c]IGIuIHRoZSBzYW1lIGFzIHRoZSBuYWlsIGl0IGNhbWUgZnJvbS48YnIgLz4K[c]IGMuIG1vcmUgdGhhbiB0aGUgbmFpbC BpdCBjYW1lIGZyb20uPGJyIC8+Cg==[c]IGQuIEl0IGlzIGltcG9zc2libGUgdG8gcHJlZGljdC48L3A+CjxwPlshISFdICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjsmIzgyMTI7IDE5ICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjstIFsvISEhXTxiciAvPgo=[q] What is the reason for your answer to the previous question?
(Iron combines with oxygen and water from the air to form rust. If an iron nail were allowed to rust completely, one should find that the rust weighs…)
[c]IGEuIFJ1c3RpbmcgbWFrZXMgdGhlIG5haWwgbGlnaHRlci48YnIgLz4K[c]IGIuIFJ1c3QgY29udGFpbnMgaXJv biBhbmQgb3h5Z2VuLjxiciAvPgo=[c]IGMuIFRoZSBuYWlsIGZsYWtlcyBhd2F5LjxiciAvPgo=[c]IGQuIFRoZSBpcm9uIGZyb20gdGhlIG5haWwgaXMgZGVzdHJveWVkLjxiciAvPgo=[c]IGUuIFRoZSBmbGFreSBydXN0IHdlaWdocyBsZXNzIHRoYW4gaXJvbi48L3A+CjxwPlshISFdICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjsmIzgyMTI7IDIwICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjstIFsvISEhXTxiciAvPgo=[q] Salt is added to water and the mixture is stirred until no more salt dissolves. The salt that does not dissolve is allowed to settle out. What happens to the concentration of salt in solution if water evaporates until the volume of the solution is half the original volume? (Assume temperature remains constant.)

The concentration
[c]IGEuIGluY3JlYXNlcy48YnIgLz4K[c]IGIuIGRlY3JlYXNlcy48YnIgLz4K[c]IGMuIHN0YXlzIHRoZSBzYW1lLjwvcD4KPHA+WyEhIV0gJiM4MjEyOyYjODIxMjsmIzgyMTI7JiM4Mj EyOyYjODIxMjsgMjEgJiM4MjEyOyYjODIxMjsmIzgyMTI7JiM4MjEyOy0gWy8hISFdPGJyIC8+Cg==[q] What is the reason for your answer to the previous question?
(Salt is added to water and the mixture is stirred until no more salt dissolves. The salt that does not dissolve is allowed to settle out. What happens to the concentration of salt in solution if water evaporates until the volume of the solution is half the original volume?)
[c]IGEuIFRoZXJlIGlzIHRoZSBzYW1lIGFtb3VudCBvZiBzYWx0IGluIGxlc3Mgd2F0ZXIuPGJyIC8+Cg==[c]IGIuIE1vcmUgc29saWQgc2 FsdCBmb3Jtcy48YnIgLz4K[c]IGMuIFNhbHQgZG9lcyBub3QgZXZhcG9yYXRlIGFuZCBpcyBsZWZ0IGluIHNvbHV0aW9uLjxiciAvPgo=[c]IGQuIFRoZXJlIGlzIGxlc3Mgd2F0ZXIuPGJyIC8+ClshISFdICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjsmIzgyMTI7IDIyICYjODIxMjsmIzgyMTI7JiM4MjEyOyYjODIxMjstIFsvISEhXTxiciAvPgo=[q] Following is a list of properties of a sample of solid sulfur:

i. Brittle, crystalline solid.
ii. Melting point of 113oC.
iii. Density of 2.1 g/cm3.
iv. Combines with oxygen to form sulfur dioxide

Which, if any, of these properties would be the same for one single atom of sulfur obtained from the sample?
[c]IGEuIGkgYW5kIGlpIG9ubHkuPGJyIC8+Cg==[c]IGIuIGlpaSBhbmQgaXYgb25seS48YnIgLz4K[c]IGMuIGl2IG9ubH kuPGJyIC8+Cg==[c]IGQuIEFsbCBvZiB0aGVzZSBwcm9wZXJ0aWVzIHdvdWxkIGJlIHRoZSBzYW1lLjxiciAvPgo=[c]IGUuIE5vbmUgb2YgdGhlc2UgcHJvcGVydGllcyB3b3VsZCBiZSB0aGUgc2FtZS48L3A+CjxwPg==[/qwiz]

An article from the Journal of Chemical Education describing the development of the test and results is here.