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scZoUnD [109]
3 years ago
13

Cu (II) sulfate exists as a hydrate. It has many practical uses including use as a fungicide and pesticide. When mixed with chro

mium and arsenic it forms the wood preservative called CCA. CCA was used in pressure treated wood to protect wood from rotting due to insects and microbial agents. Because CCA treated wood contains toxic heavy metals, its use has been discontinued for home use and children’s play sets. 1. A chemist is given a sample of the CuSO4 hydrate and asked to determine the empirical formula of it. The original sample weighed 42.75 g. After heating to remove the waters of hydration, the sample weighed 27.38 g. Determine the formula for this hydrate.
Chemistry
1 answer:
Feliz [49]3 years ago
6 0

Answer:

CuSO4.5H2O

Explanation:

Recall that;

mass of anhydrous salt/ molar mass of anhydrous salt  = mass of hydrated salt/molar mass of hydrated salt

mass of anhydrous salt =  27.38 g

mass of hydrated salt = 42.75 g

molar mass of anhydrous salt = 160 g/mol

molar mass of hydrated salt = 160 + 18x

27.38 g/160 g/mol = 42.75 g/160 + 18x

27.38 (160 + 18x) =160 * 42.75

4380.8 + 492.84x = 6840

492.84x = 6840 - 4380.8

492.84x = 2459.2

x = 2459.2/492.84

x = 5

Hence the formula of the hydrate is; CuSO4.5H2O

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4 0
3 years ago
How many moles of Carbon are in 3.06 g of Carbon
natta225 [31]

Answer:

\boxed {\boxed {\sf 0.255 \ mol \ C }}

Explanation:

If we want to convert from grams to moles, the molar mass is used. This is the mass of 1 mole. They are found on the Periodic Table as the atomic masses, but the units are grams per mole (g/mol) instead of atomic mass units (amu).

Look up the molar mass of carbon.

  • Carbon (C): 12.011 g/mol

Set up a ratio using the molar mass.

\frac {12.011 \ g \ C}{ 1 \ mol \ C}

Since we are converting 3.06 grams to moles, we multiply by that value.

3.06 \ g \ C*\frac {12.011 \ g \ C}{ 1 \ mol \ C}

Flip the ratio. This way, the ratio is still equivalent, but the units of grams of carbon cancel.

3.06 \ g \ C* \frac{1 \ mol \ C}{12.011 \ g\ C}                      

3.06 * \frac{1 \ mol \ C}{12.011 }    

\frac {3.06}{12.011 } \ mol \ C                                

0.25476646 \ mol \ C

The original measurement of grams (3.06) has 3 significant figures, so our answer must have the same. For the number we calculated, that is the thousandth place.

  • 0.25476646

The 7 in the ten-thousandth place tells us to round the 4 up to a 5.

0.255 \ mol \ C

3.06 grams of carbon is approximately <u>0.255 moles of carbon.</u>

3 0
3 years ago
List the advantages and disadvantages of restricting antibioticuse
vlada-n [284]

Answer:

Advantages - less chances of developing resistant strains, less cost, less side effects, allowing the body to mount immune response

Disadvantages - inadequate/incomplete cure leading to complications, longer stay in the hospital

Explanation:

3 0
4 years ago
What is the molarity of a solution composed of 5.85 g of potassium iodide, KI, dissolved
Troyanec [42]

Answer:

0.282 M

General Formulas and Concepts:

<u>Chemistry - Solutions</u>

  • Reading a Periodic Table
  • Using Dimensional Analysis
  • Molarity = moles of solute / liters of solution

Explanation:

<u>Step 1: Define</u>

5.85 g KI

0.125 L

<u>Step 2: Identify Conversions</u>

Molar Mass of K - 39.10 g/mol

Molar Mass of I - 126.90 g/mol

Molar Mass of KI - 39.10 + 126.90 = 166 g/mol

<u>Step 3: Convert</u>

<u />5.85 \ g \ KI(\frac{1 \ mol \ KI}{166 \ g \ KI} ) = 0.035241 mol KI

<u>Step 4: Find Molarity</u>

M = 0.035241 mol KI / 0.125 L

M = 0.281928

<u>Step 5: Check</u>

<em>We are given 3 sig figs. Follow sig fig rules and round.</em>

0.281928 M ≈ 0.282 M

7 0
3 years ago
PLEASE ANSWER Which is/are true?
Alona [7]

You have to check each statement, so this is equivalent to 5 different questions.

<u>Answers:</u>

The true statements are:

  • b. Si has valence electrons in the n = 3 energy level.

  • d. Xe has valence electrons in the n = 5 energy level.

<u>Explanations:</u>

<u>a. Li has valence electrons in the n = 1 energy level.</u>

  • <u>Answer: False.</u>

<em>Valence electrons</em> are the electrons in the outermost main energy level (shell of electrons).

To determine where the valence electrons are, you build the electron configuration, using Aufbau rules to predict the orbital filling: in increasing order of energy.

The atomic number of lithium (Li) is 3. Hence, you have to distribute 3 electrons, and so its electron confiuration is:

  • 1s² 2s¹

The only valence electron is in the 2s orbital, i.e. in the n = 2 energy level.

<u>b. Si has valence electrons in the n = 3 energy level.</u>

  • <u>Answer: True</u>

Silicon (Si) has atomic number 14, so you have to distribute 14 electrons in increasing order of energy:

  • 1s² 2s² 2p⁶ 3s² 3p²

Thus, Si has five valence electrons, and they are in the n = 3 energy level.

<u>c. Ga has valence electrons in the n = 3 energy level.</u>

  • <u>Answer: False</u>

Gallium has atomic number 31, so you have to distribute 31 electrons, filling the orbitals in increasing order of enery.

  • 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p¹

The highest energy level is 4. This is where the valence electrons are. So, Ga has the valence electrons in the n = 4 level (not n = 3 as the statement describes).

<u>d. Xe has valence electrons in the n = 5 energy level.</u>

  • <u>Answer: True</u>

The atomic number of Xe is 54.

Using the short notation (noble gas notation), and filling the orbitals in increasing order of energy, you get the configuration:

  • [Kr] 5s² 4d¹⁰ 5p⁶.

Hence, the valence electrons are in the n ) 5 level, such as the statement describes.

<u>e. P has valence electrons in the n = 2 energy level.</u>

  • <u>Answer: False</u>

Phosphorus (P) has atomic number 15, hence there are 15 electrons.

The electron configuration following the increasing order of energy, which you can remember using Aufbau rules, is:

  • 1s² 2s² 3s² 3p³

Then, the valence electrons are in the n = 3 energy level; not in the n = 2 energy level.

3 0
3 years ago
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