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3 years ago

Explain how creativity can play a role in the construction of scientific questions and hypotheses.

1 answer:

4 0

Scientific questions and hypotheses come up frequently while one is engaged in investigating a scientific phenomenon such as natural geological phenomena as may occur in geological mapping in the field. For example, there may be a question does this canyon or deeply incised valley which is quite straight follow a weakness in the earth's crust like a major fault or the direction of bedding in well bedded sedimentary rocks. In a particular topographic area, some hypotheses which may be developed is that valleys follow geological structure whereas ridges follow resistant rocks like quartzites or quartz sandstones or in the ocean, points or capes may represent resistant quartz sandstones and bays may represent weak soft shales recessively weathering

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As the temperature of a liquid increases, the solubility of a gas in the liquid

RoseWind [281]

The correct answer is B. Solubility describes the amount of solute that can be dissolved in a solvent. This value is not constant is affected by many factors. One factor is the temperature. An increase in temperature, a corresponding change in solubility also can be observed. The increase leads to a decrease in the solubility and the opposite. A decrease is observed since gas molecules are now has enough energy to escape the liquid phase and go to the gas phase.

4 0

2 years ago

In general, the value of the equilibrium constant for a chemical reaction does NOT depend on_________.

mart [117]

Answer: Option (B) is the correct answer.

Explanation:

Equilibrium constant is defined as the relationship present between the amounts of products and reactants which are there at equilibrium in a reversible chemical reaction at a given temperature.

For example, $A + B \rightleftharpoons C + D$

Mathematically, $K_{eq} = [C][D]$

As the value of equilibrium constant depends on rate constants of the forward and reverse reactions. And, this rate of reaction also changes with change in pressure and temperature.

Therefore, it will also lead to change in equilibrium constant but it does not depend on initial amount pf reactants.

Thus, we can conclude that in general, the value of the equilibrium constant for a chemical reaction does NOT depend on the initial amounts of reactants present.

4 0

2 years ago

Please give me the answer please

zepelin [54]

Answer:

A. 30cm³

Explanation:

Based on the chemical reaction:

CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂

1 mol of calcium carbonate reacts with 2 moles of HCl to produce 1 mol of CO₂

To solve this question we must convert the mass of each reactant to moles. With the moles we can find limiting reactant and the moles of CO₂ produced. Using PV = nRT we can find the volume of the gas:

Moles CaCO₃ -Molar mass: 100.09g/mol-

1.00g * (1mol / 100.09g) = 9.991x10⁻³ moles

Moles HCl:

50cm³ = 0.0500dm³ * (0.05 mol / dm³) = 2.5x10⁻³ moles

For a complete reaction of 2.5x10⁻³ moles HCl there are necessaries:

2.5x10⁻³ moles HCl * (1mol CaCO₃ / 2mol HCl) = 1.25x10⁻³ moles CaCO₃. As there are 9.991x10⁻³ moles, HCl is limiting reactant.

The moles produced of CO₂ are:

2.5x10⁻³ moles HCl * (1mol CO₂ / 2mol HCl) = 1.25x10⁻³ moles CO₂

Using PV = nRT

Where P is pressure = 1atm assuming STP

V volume in L

n moles = 1.25x10⁻³ moles CO₂

R gas constant = 0.082atmL/molK

T = 273.15K at STP

V = nRT / P

1.25x10⁻³ moles * 0.082atmL/molK*273.15K / 1atm = V

0.028L = V

28cm³ = V

As 28cm³ ≈ 30cm³

Right option is:

5 0

3 years ago

Determine the pH of a solution of 0.00278 M of HClO4. Report the answer to two digits past the decimal.

aleksandrvk [35]

Answer:

The pH of a solution of 0.00278 M of HClO₄ is 2.56

Explanation:

pH is a measure of acidity or alkalinity that indicates the amount of hydrogen ions present in a solution or substance and is calculated as:

pH= - log [H⁺]= - log [H₃O⁺]

On the other hand , a Strong Acid is that acid that in an aqueous solution dissociates completely. In other words, a strong acid completely dissociates into hydrogen ions and anions in solution.

HClO₄ is a strong acid, so in aqueous solution it will be totally dissociated. Then, the concentration of protons is equal to the initial concentration of acid and the pH will be calculated:

pH= - log 0.00278

pH= 2.56

The pH of a solution of 0.00278 M of HClO₄ is 2.56

8 0

3 years ago

II. Ionic Equations

mario62 [17]

Answer:

Complete ionic: $\begin{aligned}& \rm 2\, Ag^{+}\, (aq) + 2\, {NO_3}^{-} \, (aq) + Ca^{2+}\, (aq) + 2\, Cl^{-}\, (aq) \\ & \rm \to 2\, AgCl\, (s) + Ca^{2+}\, (aq) + 2\, {NO_3}^{-}\, (aq)\end{aligned}$ .

Net ionic: $\begin{aligned}& \rm Ag^{+}\, (aq) + Cl^{-}\, (aq) \to AgCl\, (s)\end{aligned}$ .

Explanation:

Start by identifying species that exist as ions. In general, such species include:

Soluble salts.
Strong acids and strong bases.

All four species in this particular question are salts. However, only three of them are generally soluble in water: $\rm AgNO_3$ , $\rm CaCl_2$ , and $\rm Ca(NO_3)_2$ . These three salts will exist as ions:

Each $\rm AgNO_3\, (aq)$ formula unit will exist as one $\rm Ag^{+}$ ion and one $\rm {NO_3}^{-}$ ion.
Each $\rm CaCl_2$ formula unit will exist as one $\rm Ca^{2+}$ ion and two $\rm Cl^{-}$ ions (note the subscript in the formula $\rm CaCl_2\!$ .)
Each $\rm Ca(NO_3)_2$ formula unit will exist as one $\rm Ca^{2+}$ and two $\rm {NO_3}^{-}$ ions.

On the other hand, $\rm AgCl$ is generally insoluble in water. This salt will not form ions.

Rewrite the original chemical equation to get the corresponding ionic equation. In this question, rewrite $\rm AgNO_3$ , $\rm CaCl_2$ , and $\rm Ca(NO_3)_2$ (three soluble salts) as the corresponding ions.

Pay attention to the coefficient of each species. For example, indeed each $\rm AgNO_3\, (aq)$ formula unit will exist as only one $\rm Ag^{+}$ ion and one $\rm {NO_3}^{-}$ ion. However, because the coefficient of $\rm AgNO_3\, (aq)\!$ in the original equation is two, $\!\rm AgNO_3\, (aq)$ alone should correspond to two $\rm Ag^{+}\!$ ions and two $\rm {NO_3}^{-}\!$ ions.

Do not rewrite the salt $\rm AgCl$ because it is insoluble.

$\begin{aligned}& \rm 2\, Ag^{+}\, (aq) + 2\, {NO_3}^{-} \, (aq) + Ca^{2+}\, (aq) + 2\, Cl^{-}\, (aq) \\ & \rm \to 2\, AgCl\, (s) + Ca^{2+}\, (aq) + 2\, {NO_3}^{-}\, (aq)\end{aligned}$ .

Eliminate ions that are present on both sides of this ionic equation. In this question, such ions include one unit of $\rm Ca^{2+}$ and two units of $\rm {NO_3}^{-}$ . Doing so will give:

$\begin{aligned}& \rm 2\, Ag^{+}\, (aq) + 2\, Cl^{-}\, (aq) \to 2\, AgCl\, (s)\end{aligned}$ .

Simplify the coefficients:

$\begin{aligned}& \rm Ag^{+}\, (aq) + Cl^{-}\, (aq) \to AgCl\, (s)\end{aligned}$ .

7 0

2 years ago