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garri49 [273]
3 years ago
12

How many moles are in .5g of sodium bromide?

Chemistry
1 answer:
3241004551 [841]3 years ago
8 0

Answer: 4.86 x 10⁻³ mole.

Explanation:

  • The number of moles can be calculated using the relation; n = mass / molar mass.
  • n is the number of moles, mass is the mass of the substance in g (m = 0.5 g), and molar mass of NaBr = 102.894 g/mole.
  • n = mass / molar mass = (0.5 g) / (102.894 g/mole) = 4.86 x 10⁻³ mole.
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When a 2.00 g sample of KCl is dissolved in water in a calorimeter that has a total heat capacity of 1.28 kJ ⋅ K − 1 , the tempe
Alchen [17]

Answer : The molar heat of solution of KCl is, 17.19 kJ/mol

Explanation :

First we have to calculate the heat of solution.

q=c\times (\Delta T)

where,

q = heat produced = ?

c = specific heat capacity of water = 1.28kJ/K

\Delta T = change in temperature = 0.360 K

Now put all the given values in the above formula, we get:

q=1.28kJ/K\times 0.360K

q=0.4608kJ=460.8J

Now we have to calculate the molar heat solution of KCl.

\Delta H=\frac{q}{n}

where,

\Delta H = enthalpy change = ?

q = heat released = 460.8 J

m = mass of KCl = 2.00 g

Molar mass of KCl = 74.55 g/mol

\text{Moles of }KCl=\frac{\text{Mass of }KCl}{\text{Molar mass of }KCl}=\frac{2.00g}{74.55g/mole}=0.0268mole

Now put all the given values in the above formula, we get:

\Delta H=\frac{460.8J}{0.0268mole}

\Delta H=17194.029J/mol=17.19kJ/mol

Therefore, the molar heat of solution of KCl is, 17.19 kJ/mol

7 0
3 years ago
Cellulose and starch are examples of:
mixer [17]

Answer:

The choose (d)

d. polysaccharides

3 0
3 years ago
Read 2 more answers
Which statement describes the relationship between the scientific method in the scientific process
Oksana_A [137]

Answer: The methodology is the science that addresses these issues.

Explanation:

There are several steps to exploring to obtain valid scientific results. The scientific method is one of those elements. The scientific method involves specific steps that need to be taken to begin the scientific process adequately. By the scientific method, we also mean the hypothesis or assumption that needs to be put in the paper to try to defend it later and in fact. By scientific process, we suggest the following steps we take after evaluating a hypothesis. The scientific method is the very making of a particular scientific work, that is, its central part.

7 0
3 years ago
Given the following equation: 2K + Cl2 -> 2KCl How many grams of KCl is produced from 4.00 g of K and excess Cl2?
Thepotemich [5.8K]

Answer:

42.65g

Explanation:

Given parameters:

Mass of K = 4g

Unknown: Mass of KCl

Solution:

  Complete equation of the reaction:

              2K + Cl₂ → 2KCl

To solve this problem, we know that the reactant in short supply is potassium K and this dictates the amount of products that would be formed. The chlorine gas is in excess and we can't use it to determine the amount of product that would form.

Now, we work from the known to the unknown. Since we know the mass of K given in the reaction, we can simply find the molar relationship between the reacting potassium and the product. We simply convert the mass to mole and compare to the product. From there we can find the mass of KCl that would be produced.

Calculating number of moles of K

      Number of moles = \frac{mass}{molar mass}

        Number of moles of K =  \frac{4}{39} = 0.103mol

From the given reaction equation:

   2 moles of K will produce 2 moles of KCl

 Therefore 0.103mol of K will produce 0.103mol of KCl

To find the mass of KCl produced,

   Mass of KCl = number of moles of KCl x molar mass

Molar mass of KCl = 39 + 35.5 = 74.5gmol⁻¹

Mass of KCl = 0.103 x 74.5 = 42.65g

4 0
3 years ago
Read 2 more answers
16.
mixas84 [53]

Answer:

Explanation:

When going from top to bottom in any group of the periodic table, the atomic radius always tends to increase

8 0
3 years ago
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