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3 years ago

Which substance has a molar mass of 33.99 g/mol?

Chemistry

1 answer:

alex41 [277]3 years ago

6 0

Answer:

PH₃.

Explanation:

Hello.

In this case, among the options:

PH₃, GaF₃, SF₂ and CO₂

We compute their molar masses by adding the atomic masses of the constituting elements by their subscripts:

$M_{PH_3}=m_P+3*m_H=30.97+3*1.01=34.00g/mol\\\\M_{GaF_3}=m_{Ga}+3*m_F=69.72+3*19.00=126.72g/mol\\\\M_{SF_2}=m_{S}+2*m_F=32.07+2*19.00=70.07g/mol\\\\M_{CO_2}=m_{C}+2*m_O=12.01+2*16.00=44.01g/mol$

Thus, the answer is PH₃.

Best regards.

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jonny [76]

Answer:

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2 years ago

Two 10g blocks, one of copper and one of iron, were heated from 300 K to 400K (a temperature difference of 100 K).

12345 [234]

1) 385 J

2) 450 J

Explanation:

The amount of energy that must be absorbed by a certain substance in order to increase its temperature by $\Delta T$ is given by the equation:

$Q=mC\Delta T$

where

m is the mass of the substance

C is its specific heat capacity

$\Delta T$ is the increase in temperature of the substance

For the block of copper in this problem, we have:

m = 10 g is the mass

$C=0.385 J/gK$ is the specific heat capacity of copper

$\Delta T=400-300 = 100 K$ is the change in temperature

So, the energy absorbed by the block of copper is

$Q=(10)(0.385)(100)=385 J$

Similarly for the block of iron, the energy absorbed by the iron is given by

$Q=mC\Delta T$

where

m is the mass of the block of iron

C is its specific heat capacity of iron

$\Delta T$ is the increase in temperature of the block

Here we have:

m = 10 g is the mass of the block

$C=0.450 J/gK$ is the specific heat capacity of iron

$\Delta T=400-300 = 100 K$ is the change in temperature

So, the energy absorbed by the block of iron is

$Q=(10)(0.450)(100)=450 J$

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2 years ago

Assuming complete dissociation, what is the ph of a 3.24 mg/l ba(oh)2 solution?

weqwewe [10]

We need to first find the molarity of Ba(OH₂) solution.
A mass of 3.24 mg is dissolved in 1 L solution.
Ba(OH)₂ moles dissolved - 3.24 x 10⁻³ g/171.3 g/mol = 1.90 x 10⁻⁵ mol
dissociaton of Ba(OH)₂ is as follows;
Ba(OH)₂ --> Ba²⁺ + 2OH⁻
1 mol of Ba(OH)₂ dissociates to form 2OH⁻ ions.
Therefore [OH⁻] = (1.90 x 10⁻⁵)x2 = 3.8 x 10⁻⁵ M
pOH = -log[OH⁻]
pOH = -log (3.8 x 10⁻⁵)
pOH = 4.42
pH + pOH = 14
therefore pH = 14 - 4.42
pH = 9.58

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3 years ago

What are three factors that control deep currents?

Lyrx [107]

Global winds, coriolis effect and <span>continental deflections. Hope this helps!</span>

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3 years ago

when copper sulfide is partially roasted in air (reaction with o2), copper sulfite is formed first. subsequently, upon heating,

Lyrx [107]

The question is incomplete, complete question is:

When copper(I) sulfide is partially roasted in air (reaction with oxygen), copper(I) sulfite is formed first. subsequently, upon heating, the copper sulfite thermally decomposes to copper(I) oxide and sulfur dioxide. Write balanced chemical equations for these two reactions.

Answer:

The balanced chemical equations for these two reactions:

$2Cu_2S(s)+3O_2(g)\rightarrow 2Cu_2SO_3(s)$

$Cu_2SO_3(s)\overset{heat}\rightarrow Cu_2O(s)+SO_2(g)$

Explanation:

On partial roasting of copper sulfide in an air. The balanced chemical reaction is given as:

$2Cu_2S(s)+3O_2(g)\rightarrow 2Cu_2SO_3(s)$

On further heating of copper(I) sulfite it get decomposes into copper oxide and sulfur dioxide. The balanced chemical reaction is given as:

$Cu_2SO_3(s)\overset{heat}\rightarrow Cu_2O(s)+SO_2(g)$

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3 years ago