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djverab [1.8K]
3 years ago
5

23. Using the periodic table, what is the oxidation number of:

Chemistry
1 answer:
Aloiza [94]3 years ago
8 0

Answer:

a. +2

b. +3

c. -1

Explanation:

The typical oxidation states can be determined from the periodic table based on the number of valence electrons an atom has.

a. Calcium belongs to group 2A, meaning it has 2 valence electrons and, therefore, would have an oxidation state of +2 in compounds.

b. Aluminum is in group 3A, meaning it has 3 valence electrons and would have an oxidation state of +3 in compounds when the 3 electrons are lost.

c. Fluorine would become fluorine if it gained 1 additional electron to achieve an octet, so its oxidation state would be -1.

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Can someone answer an easy chemistry question? A chemistry grad student measures the performance of the new pump in his lab. The
ella [17]
This problem requires our calculation to undergo the dimensional analysis approach. In this approach, you disregard the actual quantity and focus on the units of measurement. This helps us know the units of our final answer. 

First, let's ignore 16. Let's focus on converting the units kPa-mm³/s to mJ/s. The unit kPa stands for kiloPascals which is 1000 times greater than 1 Pa. The unit mJ, on the other hand, stands for millijoules, which is 1000 times lesser than Joules. The relationship between the two is that, Joules = Pa × m³. But since we want our final answer to be mJ, that would be equal to Pa×mm³. Since the original unit already contains mm³, all we have to do is convert kPa to Pa. 

16 kPa-mm³/s * (1000 Pa/1 kPa) = 16,000 Pa-mm³/s

Since Pa-mm³ is equal to mJ, the final conversion yields to 16,000 Pa-mm³/s.
7 0
2 years ago
Read 2 more answers
1. The speed limit on most city streets is (25 miles). How many meters per minute
irina1246 [14]

Answer:

Speed = 670.56 \frac{m}{min}

Explanation:

Given

Speed = \frac{25 mi}{hr}

Required

Convert to meters per minutes

Speed = \frac{25 mi}{hr}

Start by converting the speed from miles to meters

1\ mile = 1609.34\ meters.

So, we have:

Speed = \frac{25 * 1609.34\ m}{hr}

Speed = \frac{40233.5\ m}{hr}

Next, we convert time from hours to minutes

1\ hour = 60\ minutes

So, we have:

Speed = \frac{40233.5\ m}{60\ min}

Speed = 670.56 \frac{m}{min}

<em>Hence, the equivalent of 25 miles per hour is 670.56 meters per minutes</em>

3 0
2 years ago
If a neutral atom with 88 electrons undergoes 2 rounds of beta minus decay, what will be the new element?
Charra [1.4K]

Answer:

The new element will be thorium-226 (²²⁶Th).

Explanation:

The beta decay is given by:

^{A}_{Z}X \rightarrow ^{A}_{Z+1}Y + \beta^{-} + \bar{\nu_{e}}

Where:

A: is the mass number

Z: is the number of protons  

β⁻: is a beta particle = electron

\bar{\nu_{e}}: is an antineutrino

The neutral atom has 88 electrons, so:

e^{-} = 88 = Z

Hence the element is radium (Ra), it has A = 226.

If Ra undergoes 2 rounds of beta minus decay, we have:

^{226}_{88}Ra \rightarrow ^{226}_{89}Ac + \beta^{-} + \bar{\nu_{e}}    

^{226}_{89}Ac \rightarrow ^{226}_{90}Th + \beta^{-} + \bar{\nu_{e}}

Therefore, if a neutral atom with 88 electrons undergoes 2 rounds of beta minus decay the new element will be thorium-226 (²²⁶Th).

I hope it helps you!    

8 0
2 years ago
Pls help ASAP I’ll mark BRAINLIEST this is science btw.
Dmitrij [34]

Answer:

It should be Magnetic fields can push and pull objects without touching

but I only say with touching. Maybe it's an error on you're teachers/Prof behalf.

3 0
2 years ago
Calculate the standard enthalpy change for the reaction at 25 ∘C. Standard enthalpy of formation values can be found in this lis
weqwewe [10]

Answer:

\Delta H_{rxn}=-2043.999kJ

Explanation:

\Delta H_{rxn}^{0}=\sum [n_{i}\times \Delta H_{f}^{0}(product)_{i}]-\sum [n_{j}\times \Delta H_{f}^{0}(reactant_{j})]

Where n_{i} and n_{j} are number of moles of product and reactant respectively (equal to their stoichiometric coefficient).

\Delta H_{f}^{0} is standard heat of formation and \Delta H_{rxn}^{0} is standard enthalpy change for reaction at 25^{0}\textrm{C}

So, \Delta H_{rxn}=[3mol\times \Delta H_{f}^{0}(CO_{2})_{g}]+[4mol\times \Delta H_{f}^{0}(H_{2}O)_{g}]-[1mol\times \Delta H_{f}^{0}(C_{3}H_{8})_{g}]-[5mol\times \Delta H_{f}^{0}(O_{2})_{g}]

or, \Delta H_{rxn}=[3mol\times -393.509kJ/mol]+[4mol\times -241.818kJ/mol]-[1mol\times -103.8kJ/mol]-[5mol\times 0kJ/mol]

or, \Delta H_{rxn}=-2043.999kJ

4 0
3 years ago
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