The table gives the solubility of each substance in 100

Calculate the moles of solute dissolved in 4.2 dm3 of a 0.5 mol / dm3 solution.

Archy [21]

Answer:

Example

0.5 mol of sodium hydroxide is dissolved in 2 dm3 of water. Calculate the concentration of the sodium hydroxide solution formed.

Concentration =

Concentration = 0.25 mol/dm3

Volume units

Volumes used in concentration calculations must be in dm3, not in cm3. It is useful to know that 1 dm3 = 1000 cm3. This means:

divide by 1000 to convert from cm3 to dm3

multiply by 1000 to convert from dm3 to cm3

For example, 250 cm3 is 0.25 dm3 (250 ÷ 1000). It is often easiest to convert from cm3 to dm3 before continuing with a concentration calculation.

Question

100 cm3 of dilute hydrochloric acid contains 0.02 mol of dissolved hydrogen chloride. Calculate the concentration of the acid in mol/dm3.

Reveal answer

Converting between units

The relative formula mass of the solute is used to convert between mol/dm3 and g/dm3:

to convert from mol/dm3 to g/dm3, multiply by the relative formula mass

to convert from g/dm3 to mol/dm3, divide by the relative formula mass

Remember: the molar mass is the Ar or Mr in grams per mol.

Example

Calculate the concentration of 0.1 mol/dm3 sodium hydroxide solution in g/dm3. (Mr of NaOH = 40)

Concentration = 0.1 × 40

= 4 g/dm3

8 0

3 years ago

The quantity, 1,385 mg is equivalent to in scientific notation

Agata [3.3K]

Answer:

The answer is 1385 x10∧ -3

Explanation:

Scientific notation is a quick way to represent a number using notation in exponential form or powers of base ten.

This notation allows us to express too large or small numbers easily.

For example:

500 is written as 5x10∧2; Where the power 2 represents the number of 0's that follow 5.

0.0093 is written as 9.3x10∧-3; Where the power -3 represents the number of times the comma was moved to the right.

8 0

3 years ago

C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(l), ΔH = –1.37 × 103 kJ For the combustion of ethyl alcohol as described in the above equati

babymother [125]

Answer:

The true statements are: I. The reaction is exothermic.

II. The enthalpy change would be different if gaseous water was produced.

Explanation:

The given chemical reaction: C₂H₅OH(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(l), ΔH= -1.37×10³kJ

1. In an exothermic reaction, heat or energy is released from the system to the surrounding. Thus for an exothermic process the change in enthalpy is less than 0 or negative (ΔH < 0) .

Since the enthalpy change for a combustion reaction is negative. Therefore, the given reaction is exothermic.

2. The change in enthalpy (ΔH) of a reaction is equal to difference of the sum of standard enthalpy of formation (ΔHf°) of the products and the reactants.

ΔHr° = ∑ n.ΔHf°(products) − ∑ n.ΔHf°(reactants)

As the value of ΔHf° of water in gaseous state and liquid state is not the same.

Therefore, the enthalpy change of the reaction will be different, if gaseous water was present instead of liquid water.

3. An oxidation-reduction reaction or a redox reaction involves simultaneous reduction and oxidation processes.

The given chemical reaction, represents the combustion reaction of ethanol.

Since combustion reactions are redox reactions. Therefore, the given combustion reaction is an oxidation-reduction reaction.

4. According to the ideal gas equation: P.V =n.R.T

Volume (V) ∝ n (number of moles of gas)

Since the number of moles (n) of gaseous reactants is 3 and number of moles of gaseous (n) products is 2.

Therefore, the volume occupied by 3 moles of the reactant gaseous molecules will be more than 2 moles product gaseous molecules.

3 0

4 years ago

Predict: In each "Climate type" box, Highlight the condition you think will lead to the fastest weathering for the given weather

yanalaym [24]

Answer:

Frost Wedging - Hot and dry

Clay Formation - Cold and Wet

Dissolving - Cold, and dry

Explanation:

The frost wedging happen when the climatic condition is hot and dry. The dry weather compensates the heat and the rock wedging happens quickly. For clay formation the weather has to be cold and wet. The cold weather will make the sand indulge with rock particles resulting in the clay formation.

6 0

3 years ago

Draw the molecules listed below and circle any functional groups present. Provide the following information for each molecule:Mo

aksik [14]

The question requires us to draw the structural formula, provide the name and highlight any functional groups for the compound: diethyl ether.

The molecule diethyl ether can be represented as it follows, with two ethyl groups (-CH2CH3) bonded to a oxygen atom:

Note that the functional group ether (R-O-R) is present in the structre and highlighted in blue in the image. The official name of diethyl ether is ethoxyethane.

3 0

1 year ago