Metric equivalent to 4 tbsp

What type of change is the following: striking a match chemical, or physical?

chubhunter [2.5K]

Chemical,when you light a match stick, you are starting a chain reaction of the substance chemical formula, making it a chemical change

7 0

4 years ago

HClO4 acid solution has a concentration of 5 Molarity. Calculate the concentration of this solution in

Nutka1998 [239]

Answer:

1. Percentage by weight = 0.5023 = 50.23 %

2. molar fraction =0.153

Explanation:

We know that

Molar mass of HClO4 = 100.46 g/mol

So the mass of 5 Moles= 5 x 100.46

Mass (m)= 5 x 100.46 = 502.3 g

Lets assume that aqueous solution of HClO4 and the density of solution is equal to density of water.

Given that concentration HClO4 is 5 M it means that it have 5 moles of HClO4 in 1000 ml.

We know that

Mass = density x volume

Mass of 1000 ml solution = 1 x 1000 =1000 ( density = 1 gm/ml)

m'=1000 g

1.

Percentage by weight = 502.3 /1000

Percentage by weight = 0.5023 = 50.23 %

2.

We know that

molar mass of water = 18 g/mol

mass of water in 1000 ml = 1000 - 502.3 g=497.9 g

So moles of water = 497.7 /18 mole

moles of water = 27.65 moles

So molar fraction = 5/(5+27.65)

molar fraction =0.153

6 0

3 years ago

A decrease in the concentration of reactants causes the rate of the _____ reaction to slow.

nataly862011 [7]

The correct answer is a Forward reaction to slow.
According to Le Chatelier's principle as the reactant decrease so the reaction should go leftward and this is called backward or reverse reaction so the reverse reaction will be fast to achieve equilibrium and the forward reaction will be slow.

6 0

3 years ago

3.15 mol of an unknown solid is placed into enough water to make 150.0 mL of solution. The solution's temperature increases by 1

nordsb [41]

<u>Answer:</u> The enthalpy change of the unknown solid is 3.824 kJ/mol

<u>Explanation:</u>

To calculate the mass of solution , we use the equation:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$

Density of solution = 1.20 g/mL

Volume of solution = 150.0 mL

Putting values in above equation, we get:

$1.20g/mL=\frac{\text{Mass of solution}}{150.0mL}\\\\\text{Mass of solution}=(1.20g/mL\times 150.0mL)=180g$

The equation used to calculate heat released or absorbed follows:

$Q=m\times c\times \Delta T$

q = heat absorbed or released

m = mass of solution = 180 g

c = specific heat capacity = 4.18 J/g°C

$\Delta T$ = change in temperature = 16.01°C

Putting values in above equation:

$Q=180\times 4.18\times 16.01=12045.9J=12.046kJ$

To calculate the enthalpy change of the reaction, we use the equation

$\Delta H_{rxn}=\frac{q}{n}$

where,

q = amount of heat absorbed = 12.046 kJ

n = number of moles of solid = 3.15 moles

$\Delta H_{rxn}$ = enthalpy change of the reaction

Putting values in above equation, we get:

$\Delta H_{rxn}=\frac{12.046kJ}{3.15mol}=3.824kJ/mol$

Hence, the enthalpy change of the unknown solid is 3.824 kJ/mol

5 0

3 years ago

1. Define the unit 'mole'

serious [3.7K]

Answer:

Below

Explanation:

The mole, symbol mol, is the SI base unit of amount of substance. The quantity amount of substance is a measure of how many elementary entities of a given substance are in an object or sample

7 0

2 years ago

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