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Sveta_85 [38]
3 years ago
12

Element 'x' has two stable isotopes:

Chemistry
1 answer:
zalisa [80]3 years ago
6 0

Answer:

216.5 amu

Explanation:

Step 1: Given data

  • Mass of isotope ²¹⁵X (m²¹⁵X): 215 amu
  • Abundance of isotope ²¹⁵X (ab²¹⁵X): 25%
  • Mass of isotope ²¹⁷X (m²¹⁷X): 217 amu
  • Abundance of isotope ²¹⁷X (ab²¹⁷X): 75%

Step 2: Calculate the average atomic mass for the element

When an element has 2 or more isotopes, we calculate the average atomic mass (am) using the following expression.

am = ∑ mi × abi / 100%

where,

mi: mass of each isotope

abi: abundance of each isotope

am = (m²¹⁵X × ab²¹⁵X + m²¹⁷X × ab²¹⁷X) / 100%

am = (215 amu × 25% + 217 amu × 75%) / 100% = 216.5 amu

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nirvana33 [79]

Answer: The remains of plants and animals are called organic matter.

Explanation:

3 0
3 years ago
The combustion reaction described in part (b) occurred in a closed room containing 5.56 10g of air
ziro4ka [17]

Answer:

Explanation:

Combustion reaction is given below,

C₂H₅OH(l) + 3O₂(g) ⇒ 2CO₂(g) + 3H₂O(g)

Provided that such a combustion has a normal enthalpy,

ΔH°rxn = -1270 kJ/mol

That would be 1 mol reacting to release of ethanol,

⇒ -1270 kJ of heat

Now,

0.383 Ethanol mol responds to release or unlock,

(c) Determine the final temperature of the air in the room after the combustion.

Given that :

specific heat c = 1.005 J/(g. °C)

m = 5.56 ×10⁴ g

Using the relation:

q = mcΔT

- 486.34 =  5.56 ×10⁴  × 1.005 × ΔT

ΔT= (486.34 × 1000 )/5.56×10⁴  × 1.005

ΔT= 836.88 °C

ΔT= T₂ - T₁

T₂ =  ΔT +  T₁

T₂ = 836.88 °C + 21.7°C

T₂ = 858.58 °C

Therefore, the final temperature of the air in the room after combustion is 858.58 °C

4 0
3 years ago
Help me with this question?!!​
olya-2409 [2.1K]

Answer:

500 mL

Explanation:

Step 1: Find conversions

1 mL = 0.0338 oz

Step 2: Use Dimensional Analysis

16.9 \hspace{2} oz(\frac{1 \hspace{2} mL}{0.0338 \hspace{2} oz} ) = 500 mL

3 0
3 years ago
It is found that a gas undergoes a first-order decomposition reaction. If the rate constant for this reaction is 8.1 x 10-2 /min
kap26 [50]

Answer:

28.43 min

Explanation:

Using integrated rate law for first order kinetics as:

[A_t]=[A_0]e^{-kt}

Where,  

[A_t] is the concentration at time t

[A_0] is the initial concentration

Given that:

The rate constant, k = 8.1\times 10^{-2} min⁻¹

Initial concentration [A_0] = 0.1 M

Final concentration [A_t] = 1.0\times 10^{-2} M

Time = ?

Applying in the above equation, we get that:-

1.0\times 10^{-2}=0.1e^{-8.1\times 10^{-2}\times t}

0.1e^{-8.1\times \:10^{-2}t}=10^{-2}

e^{-8.1\times \:10^{-2}t}=\frac{1}{10}

\ln \left(e^{-8.1\times \:10^{-2}t}\right)=\ln \left(\frac{1}{10}\right)

t=28.43\ min

3 0
4 years ago
A chemist needs to find the concentration of a solution of barium hydroxide.
Brums [2.3K]

Method 1: gravimetry

advantages: Impurities in the sample can be identified

disadvantages: The process is long, because it goes through several stages

Method 2: titration

advantages: the process is fast, because the titrate and titrant react immediately

disadvantages: Sometimes the determination of the end point of the titration is carried out too fast or too slowly so that the calculations carried out are inaccurate

3 0
2 years ago
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