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Blizzard [7]
2 years ago
5

A group of students working in a high school chemistry lab believe they have discovered a new element! How exciting! Upon furthe

r testing by scientists (with better equipment), it is found that the new element contains 74 protons and 110 neutrons. Use Page 495 and the Periodic Table (Pages 500-501) to answer the following questions about this new element.
1. What is the atomic number of this element? _____________¬¬___________

2. What is the mass number of this element? _________________________

3. Is this really a new element? Explain your reasoning.


4. Give the name and symbol for this element.___________________________________

5. When the students discovered it, did they find a solid, a liquid, or a gas? Explain your reasoning.
Chemistry
2 answers:
mart [117]2 years ago
4 0

Answer:

1) The atomic number of this element is 74, because number of protons = atomic number

2) Mass number of this element is 184

Ar=Z+N=74+110=184

3) It isn't a new element. An element with such atomic and mass numbers exists

4) It is Wolfram. Symbol: W

5) Solid

Sorry if I made mistakes. I started learning English recently.

kipiarov [429]2 years ago
3 0

Answer:

Explanation:

We are given that  number of protons in  new element =74

Number of neutrons in new element =110

We know that

1.Atomic number = Total number of protons

Atomic number of new element =74

Mass number = Number of protons+number of neutrons

2.Mass number of new element =74+110=184

3.It is not new element .It had already exits in periodic table.

4.Hence, the new elements is tungsten or wolfram.

Symbol of tungsten is W.

5.It is a metal and all metals except mercury are solids.Therefore, tungsten is a solid.

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Describe how you would prepare exactly 100 mL of 0.109 M picolinate buffer, pH 5.61. Possible starting materials are pure picoli
Pepsi [2]

Answer:

1.342g of picolinic acid and 6.743mL of 1.0M NaOH diluting the mixture to 100.0mL

Explanation:

<em>The pKa of the picolinic acid is 5.4.</em>

Using Henderson-Hasselbalch formula for picolinic-picolinate buffer:

pH = pKa + log [Picolinate] / [Picolinic]

<em>Where [] could be taken as moles of each species</em>

<em />

5.61 = 5.4 + log [Picolinate] / [Picolinic]

0.21 = log [Picolinate] / [Picolinic]

1.62181 = [Picolinate] / [Picolinic] <em>(1)</em>

<em></em>

Now, both picolinate and picolinic acid will be:

0.100L * (0.109mol / L) =

0.0109 moles = [Picolinate] + [Picolinic] <em>(2)</em>

<em></em>

First, as we will start with picolinic acid, we need add:

0.0109 moles picolinic acid * (123.10g/mol) = 1.342g of picolinic acid

Now, replacing (2) in (1):

1.62181 = 0.0109 moles - [Picolinic] / [Picolinic]

1.62181 [Picolinic] = 0.0109 moles - [Picolinic]

2.62181 [Picolinic] = 0.0109 moles

[Picolinic] = 4.157x10⁻³ moles

And:

[Picolinate] = 0.0109 - 4.157x10⁻³ moles =

<h3>6.743x10⁻³ moles</h3><h3 />

To obtain these moles of picolinate ion we need to make the reaction of the picolinic acid with NaOH:

Picolinic acid + NaOH → Picolinate + Water

<em>That means to obtain 6.743x10⁻³ moles of picolinate ion we need to add 6.743x10⁻³ moles of NaOH</em>

<em />

6.743x10⁻³ moles of NaOH that is 1.0M are, in mL:

6.743x10⁻³ moles * (1L / 1mol) = 6.743x10⁻³L * 1000 =

<h3>6.743mL of the 1.0M NaOH must be added</h3><h3 />

Thus, we obtain the desire moles of picolinate and picolinic acid to obtain the buffer we want, the last step is:

<h3>Dilute the mixture to 100mL, the volume we need to prepare</h3>
3 0
2 years ago
determine whether each of the following causes an increase or decrease in the activity of the electron transport chain.
viktelen [127]
The following causes increase the activity of the electron transport chain:
1. High ADP concentration
2. Large differences in H+ concentration across the inner mitochondrial membrane
3. High phosphate concentration

The following causes decrease the activity of the electron transport chain:
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2. Low NADH concentration
4 0
2 years ago
A 2.0-g sample of washing soda, Na CO • 10H O, has carbon atoms. How many oxygen atoms are present in 2.0g of washing soda?
vovikov84 [41]

Description is on the picture in attachment

7 0
2 years ago
Compound X has a molar mass of 135.13 and the following composition: element mass % carbon 44.44% hydrogen 3.73% nitrogen 51.83%
geniusboy [140]

Hello!

First, let's see what a molar mass is. A molar mass is how much a mole weighs, or how much 6.02214076×10²³ of an element weighs.

Now, let's find the molar mass of each of these three elements.

Carbon: 12.0107 g/mol

Hydrogen: 1.00784 g/mol

Nitrogen: 14.0067 g/mol

Now, see how much of the molar mass of compound x each of these contributes.

Carbon: 44.44% * 135.13 = 60.051772 g/mol

Hydrogen: 3.73% * 135.13 = 5.040349 g/mol

Nitrogen: 51.83% * 135.13 = 70.037879 g/mol

Finally, calculate how many atoms there are in the molecule. Do this my dividing the "how much they contribute to the molar mass" by the molar mass.

Carbon: 60.051772 / 12.0107 = 5

Hydrogen: 5.040349 / 1.00784 = 5

Nitrogen: 70.037879 / 14.0067 = 5

Therefore, we know that there are 5 Carbons, 5 hydrogens, and 5 nitrogens.

Put this all together to get the molecular formula: C5H5N5 (note that the numbers should be written as subscript)

Hope this helps!

7 0
2 years ago
If a 0.4856 gram sample of khp is dissolved in sufficient water to prepare 250 ml of solution, and 25 ml of the solution require
dangina [55]

Mass of potassium hydrogen pthalate KHP is 0.4856 g, its molar mass is 204.22 g/mol, number of moles of KHP can be calculated as follows:

n=\frac{m}{M}

Here, m is mass and M is molar mass, putting the values,

n=\frac{0.4856 g}{204.22 g/mol}=0.00237 mol

This will be number of moles of NaOH at equivalent point.

Detailed calculations:

Molarity is defined as number of moles in 1 L of solution, for 250 mL of solution, molarity will be:

M=\frac{0.00237 mol}{250 \times 10^{-3}L}=0.009511 M

For 25 mL, apply dilution law as follows:

M_{1}V_{1}=M_{2}V_{2}

Putting the values,

0.009511\times 250=M_{2}\times 25 mL

On rearranging,

M_{2}=\frac{0.009511\times 250}{25}=0.09511 M

Convert molarity into number of moles,

n=M\times V=0.09511 mol/L\times 25\times 10^{-3}L=0.00237 mol

At equivalent point, number of moles of KHP will be equal to NaOH, thus, number of moles of NaOH will be 0.00237 mol.

Calculation for molarity:

Volume of NaOH is 18.75 mL, thus, molarity can be calculated as follows:

M=\frac{n}{V}

Putting the values,

M=\frac{0.00237 mol}{18.75\times 10^{-3}L}=0.1264 M

Therefore, molarity of NaOH is 0.1264 M

7 0
2 years ago
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