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Alborosie
2 years ago
10

True or false, The atomic number of an element is a whole number that decreases as you read across each row of

Chemistry
1 answer:
torisob [31]2 years ago
5 0

Answer:

I believe it's false because the atomic number is the number of protons in the nucleus of an atom.

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A 126-gram sample of titanium metal is heated from 20.0°C to 45.4°C while absorbing 1.68 kJ of heat. What is the specific heat o
Radda [10]

Answer:

The specific heat for the titanium metal is 0.524 J/g°C.

Explanation:

Given,

Q = 1.68 kJ   = 1680 Joules

mass = 126 grams

T₁ = 20°C

T₂ = 45.4°C

The specific heat for the metal can be calculated by using the formula

Q = (mass) (ΔT) (Cp)

Here, ΔT =  T₂ - T₁ = 45.4 - 20 = 25.4°C.

Substituting values,

1680 = (126)(25.4)(Cp)

By solving,

Cp = 0.524 J/g°C.

The specific heat for the titanium metal is 0.524 J/g°C.

3 0
2 years ago
Calculate the mass of MNO2 needed to produce 25.0 g of Cl2
Vedmedyk [2.9K]
I will solve this question assuming the reaction equation look like this:
<span>MnO2 + 4 HCl ---> MnCl2 + Cl2 + 2 H2O. 
</span>
For every one molecule of MnO2 used, there will be one molecule of Cl2 formed. If the molecular mass of MnO2 is 87g/mol and molecular mass of Cl2 is <span> 73.0 g/mol, the mass of MnO2 needed would be:
Cl mass/Cl molecular mass * MnO2 molecular mass=
25g/ (73g/mol) * (87g/mol) * 1/1= 29.8 grams</span>
7 0
2 years ago
Read 2 more answers
A 0.2-mm-thick wafer of silicon is treated so that a uniform concentration gradient of antimony is produced. One surface contain
krek1111 [17]

Answer:

- 0.0249% Sb/cm

-1.2465 * 10^9 \frac{atoms}{cm^3.cm}

Explanation:

Given that:

One surface contains 1 Sb atom per  10⁸  Si atoms and the other surface contains 500 Sb atoms per  10⁸ Si atoms.

The concentration gradient in atomic percent (%) Sb  per cm can be calculated as follows:

The difference in concentration = \delta_c

The distance \delta_x = 0.2-mm = 0.02 cm

Now, the concentration of silicon at one surface containing  1 Sb atom per 10⁸ silicon atoms and at the outer surface that has 500 Sb atom per   10⁸ silicon atoms can be calculated as follows:

\frac{\delta_c}{\delta_c} = \frac{(1/10^8 -500/10^8)}{0.02cm} *100%

= - 0.0249% Sb/cm

b) The concentration (c_1) of Sb in atom/cm³ for the surface of 1 Sb atoms can be calculated by using the formula:

c_1 = \frac{(8 si atoms/unit cells)(1/10^3)}{(lattice parameter)^3/unit cell}

Lattice parameter = 5.4307 Å;  To cm ; we have

= 5.4307A^0* \frac{10^{-8}cm}{ A^0}

c_1 = \frac{(8 si atoms/unit cells)(1/10^8)}{(5.4307*10^{-8}cm)^3/unit cell}

= 0.00499*10^{17}atoms/cm^3

The concentration (c_2) of Sb in atom/cm³ for the surface of 500 Sb can be calculated as follows:

c_1 = \frac{(8 si atoms/unit cells)(500/10^8)}{(5.4307*10^{-8}cm)^3/unit cell}

   =  \frac{4*10^{-3}}{1.601*10^{-22}}

   = 2.4938*10^{17}atoms/cm^3

Finally, to calculate the concentration gradient

(\frac{\delta _c}{\delta_ x}) = \frac{c_1-c_2}{\delta_x}

(\frac{\delta _c}{\delta_ x}) = \frac{0.00499*10^{17}-2.493*10^{17}}{0.02}

= -1.2465 * 10^9 \frac{atoms}{cm^3.cm}

8 0
2 years ago
What could be done to change this carbide ion to a neutral carbon atom? A) remove 2 electrons B) add 2 electrons C) remove 4 ele
bonufazy [111]

Answer:remove 4 electrons

Explanation:

I took the test just a minute a go

5 0
2 years ago
What is the oxidation state of selenium in SeO3?​
ra1l [238]

Answer: The oxidation state of selenium in SeO3 is +6

Explanation:

SeO3 is the chemical formula for selenium trioxide.

- The oxidation state of SeO3 = 0 (since it is stable and with no charge)

- the oxidation number of oxygen (O) IN SeO3 is -2

- the oxidation state of selenium in SeO3 = Z (let unknown value be Z)

Hence, SeO3 = 0

Z + (-2 x 3) = 0

Z + (-6) = 0

Z - 6 = 0

Z = 0 + 6

Z = +6

Thus, the oxidation state of selenium in SeO3 is +6

8 0
2 years ago
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