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Eddi Din [679]
3 years ago
7

A student submits the following work on the mass number, but he has made a few mistakes. Select all of his mistakes.

Chemistry
2 answers:
MatroZZZ [7]3 years ago
8 0

Answer:

1. <u>Calculating the mass number for an atom requires that we know the atomic number and the number of protons in the atom's nucleus.</u>

2. <u>The mass number then gives us the average weight of atoms of a given element.</u>

3. <u>However, as long as the number of protons equals the number of neutrons, the values balance out and we always obtain a whole number for the mass number.</u>

Explanation:

MatroZZZ [7]3 years ago
4 0

Do you know the answer?

:)

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5 0
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Calculate the enthalpy for this reaction: 2C(s) + H2(g) ---&gt; C2H2(g) ΔH° = ??? kJ Given the following thermochemical equation
nordsb [41]

Answer:

The enthalpy for given reaction is 232 kilo Joules.

Explanation:

C_2H_2(g) + \frac{5}{2}O_2(g)\rightarrow 2CO_2(g) + H_2O(l), \Delta H^o_{1} = -1,123 kJ...[1]

C(s) + O_2(g)\rightarrow CO2(g), \Delta H^o_{2} = -340 kJ..[2]

H_2(g) + \frac{1}{2}O_2(g)\rightarrow H_2O(l) ,\Delta H^o_{3} = -211 kJ..[3]

2C(s) + H_2(g)\rightarrow C_2H_2(g),\Delta H^o_{4} =?..[4]

2 × [2] + [3] - [1] ( Using Hess's law)

\Delta H^o_{4}=2\times \Delta H^o_{2}+\Delta H^o_{3} - \Delta H^o_{1}

\Delta H^o_{4}=2\times (-340 kJ) + (-211 kJ) - (-1,123 kJ)

\Delta H^o_{4}=232 kJ

The enthalpy for given reaction is 232 kilo Joules.

5 0
2 years ago
If you pump air into cycle tyre a slight warming effect is noticed at valve stem why
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As the air molecules move through the valve they have friction as they hit the walls, and its this friction that causes it to heat up.

6 0
3 years ago
A balloon is filled to a volume of 1.6 L at 278 K. The balloon is left outside overnight and the temperature has dropped to 253
german

Explanation:

Charles' law gives the relationship between the volume and the temperature of the gas. Mathematically,

Volume ∝ Temperature

i.e. \dfrac{V_1}{V_2}=\dfrac{T_1}{T_2}

We have, V₁ = 1.6 L, T₁ = 278 K, T₂ = 253, V₂=?

V_2=\dfrac{V_1T_2}{T_1}\\\\V_2=\dfrac{1.6\times 253}{278}\\\\V_2=1.45\ L

So, the new volume is 1.45 L.

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3 years ago
Using tongs place the 250 mL beaker on hot plate
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Answer:

just use the tongs and put it on a plate

Explanation:

4 0
2 years ago
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