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Bezzdna [24]
3 years ago
13

Please help last assignment of the day

Chemistry
1 answer:
Andrej [43]3 years ago
3 0

In this qn, you use the mole formula,

amount (mol) = mass (g) ÷ molar mass

(molar mass is the mass number of an element, which u can find by referring to the periodic table)

so by subbing in the values given to you, you can find the answer

5. amount of Cu = 55.9 ÷ 63.5 = 0.880mol (3sf)

6. amount of N2 = 340 ÷ 2(14.0) = 12.1mol (3sf)

(note: you multiply the molar mass of N by 2 as there are 2 N atoms)

for qn 7 and 8, youre finding the mass and not the amount. By bringing the molar mass over to the other side of the formula, you get

mass = amount (mol) × molar mass

thus,

7. mass of Fe = 0.063 × 55.8 = 3.52g (3sf)

8. mass of H2 = 94.7 × 2(1.0) = 47.4g (3sf)

extra things to take note of:

- likewise, you can also find the molar mass of an element by using

molar mass = mass(g) ÷ amount(mol)

^^ this is commonly only needed when you need to find the molar mass of an isotope. the question will give you the amount and mass of the element, and you just need to factor them in to find your answer.

- typically, you use 3 sf in your final answer and 5sf in your working. remember to write (3sf) at the end of your number statement when necessary.

- when you get an answer of (eg.) 0.6mol, you still need to write it in 3sf, so your answer would be 0.600mol

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A student places three ice cubes in a beaker and allows them to partially melt. If she measures the temperature of the water in
Sonja [21]
<h2>Answers to the whole assignment:</h2>

**Check for proof photos at the bottom.**

**Answers are in bold.**

__________________________________________________________

A student places three ice cubes in a beaker and allows them to partially melt. If she measures the temperature of the water in the beaker, what will she most likely observe? Explain your answer.

She will see that the temperature of the water is 0 degrees Celsius and it stays at that temperature until all the ice cubes completely melt.

__________________________________________________________

Use the table on the right to calculate each required quantity. Record values to 3 significant digits.

First answer: 35.8 kJ

Second answer: 871 g

Third answer: Fe

__________________________________________________________

An iron sphere with a mass of 75.00 g is heated to a temperature of 385.0°C. It is then placed in a beaker containing 150.0 g H2O at 100.0°C.

First answer: 339 kJ

Second answer: 9.02  kJ

Third answer: No

__________________________________________________________

A sample of water has a mass of 100.0 g. Calculate the amount of heat required to change the sample from ice at –45.00°C to water vapor at 175.0°C. Relevant constant values are given to the right.

First answer: 325  kJ

Second answer: boiling the water

__________________________________________________________

Identify the correct description for each part labeled on the diagram.  

A: ✔ heating solid

B: ✔ melting

C: ✔ heating liquid

D: ✔ boiling

E: ✔ heating gas

F: ✔ melting point

G: ✔ boiling point

Where are the particles closest together?

✔ A

<h2>Explanation:</h2>

When ice partially melts, the surrounding water remains at 0° Celsius. This is because ice melting only involves the water molecules overcoming intermolecular forces, or forces holding molecules together. The water molecules themselves aren't increasing in kinetic energy when turning into liquid. Since temperature measures kinetic energy, the temperature in this case, remains at 0°.

To find how much energy it takes to cause a phase change in a substance, you must find the number of moles, and determine whether to use ΔHvap and ΔHfus. ΔHvap is used to show how much energy is involved in evaporation and condensation, and ΔHfus is the same but used for melting and freezing. To find number of moles of a given substance, use the formula: mass of given substance divided by atomic mass. Both numbers have to use the same mass unit. Then, multiply number of moles by ΔHvap or ΔHfus to get kJ.

In a heating curve graph, the flat lines represent no change in energy, or the phase changes. The steep lines are change in energy, which are either heating or cooling. The bottom line is a heating/cooling solid. A heating/cooling solid is the coldest phase, which is why the line is at the bottom.

Here are photos of Edge to make things easier.

7 0
2 years ago
How many grams of glucose are in 11.5 moles?
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Per 1 mole there are 180.15588 grams of glucose. 180.5588 x 11.5 =2076.4262

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An ate or ite at the end of a compound name usually indicates that the compound contains___________.
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Answer:

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3 0
3 years ago
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This question deals with waste disposal in the Solutions and Spectroscopy experiment. What should be done to waste solutions con
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Answer:

b. It should be dumped in a beaker labeled "waste copper" on one's bench during the experiment.

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Explanation:

Solutions containing copper ion should never be disposed of by dumping them in a sink or in common trash cans, because this will cause pollution in rivers, lakes and seas, being a contaminating agent to both human beings and animals. They should be placed in appropriate compatible containers that can be hermetically sealed. The sealed containers must be labeled with the name and class of hazardous substance they contain and the date they were generated.

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