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2 years ago

Science, compare and contrast Quantitative and Qualitative observations

1 answer:

6 0

Quantitative observation have accuracy over qualitative observation as in Quantitative observation data is recorded in terms of number .

Explanation:
Qualitative observations are descriptive observations that don't involve numbers. " The freezing point of water is colder than the boiling point " is an example. Quantitative observations are numerical measurements. "The freezing point of watrr is 0 c and boiling point is 100 c" is a quantitative observation.

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If the temperature of 15 grams of water changes from 21C to 24C, how many joules of heat were involved? Show work

goblinko [34]

Answer:

189 Joules

Explanation:

Applying,

Q = cm(t₂-t₁)............. equation 1

Where Q = Heat, c = specific heat capacity of water, m = mass of water, t₁ = Initial Temperature, t₂ = Final temperature.

From the question,

Given: m = 15 grams = 0.015 kg, t₁ = 21 °C, t₂ = 24 °C

Constant: c = 4200J/kg.°C

Substitute these values into equation 1

Q = 0.015×4200×(24-21)

Q = 0.015×4200×3

Q = 189 Joules

6 0

2 years ago

How many valence electrons do alkali metals have?

Lana71 [14]

1 valence electron in alkali metals.

3 0

2 years ago

Help please

andrew11 [14]

Answer:

K2Cr2O7

Explanation:

Solubility refers to the amount of substance that dissolves in a given mass or volume of solvent. There are several units of solubility applicable in different areas.

Solubility is dependent on temperature. The solubility curve is a graphical representation of the dependence of solubility on temperature for different chemical species.

If we study the solubility curve closely, we will see that K2Cr2O7 has the highest solubility at 100°C. This means that if the trends continue, this substance will also have the highest solubility at 120°C.

6 0

2 years ago

Read 2 more answers

A student is doing an experiment to determine the effects of temperature on an object. He writes down that the initial temperatu

bogdanovich [222]

Answer:

1) The Kelvin temperature cannot be negative

2) The Kelvin degree is written as K, not ºK

Explanation:

The temperature of an object can be written using different temperature scales.

The two most important scales are:

- Celsius scale: the Celsius degree is indicated with ºC. It is based on the freezing point of water (placed at 0ºC) and the boiling point of water (100ºC).

- Kelvin scale: the Kelvin is indicated with K. it is based on the concept of "absolute zero" temperature, which is the temperature at which matter stops moving, and it is placed at zero Kelvin (0 K), so this scale cannot have negative temperatures, since 0 K is the lowest possible temperature.

The expression to convert from Celsius degrees to Kelvin is:

$T(K)=T(^{\circ}C)+273.15$

Therefore in this problem, since the student reported a temperature of -3.5 ºK, the errors done are:

1) The Kelvin temperature cannot be negative

2) The Kelvin degree is written as K, not ºK

6 0

3 years ago

A synthesis reaction takes place when carbon monoxide (CO) and hydrogen gas (H2) react to form methanol (CH3OH). How many grams

jek_recluse [69]

The mass of methanol produced is 8.0 g.

We have the masses of two reactants, so this is a limiting reactant problem.

We know that we will need a balanced equation with masses, moles, and molar masses of the compounds involved.

Step 1. Gather all the information in one place with molar masses above the formulas and everything else below them.

MM: ___28.01 2.016 ___32.04

_______CO + 2H_2 → CH_3OH

Mass/g: 7.0 __2.5

Step 2. Calculate the moles of each reactant

Moles of CO = 7.0 g CO × (1 mol CO/28.01g CO) = 0.250 mol CO

Moles of H_2 =2.5 g H_2 × (1 mol H_2/2.016 g H_2) = 1.24 mol H_2

Step 3. Identify the limiting reactant

Calculate the moles of CH_3OH we can obtain from each reactant.

From CO: Moles of CH_3OH = 0.250 mol CO × (1 mol CH_3OH /1 mol CO)

= 0.250 mol CH_3OH

From H_2: Moles of CH_3OH = 1.24 mol H_2 × (1 mol CH_3OH /2 mol H_2)

= 0.620 mol CH_3OH

CO is the limiting reactant because it gives the smaller amount of CH_3OH.

Step 4. Calculate the mass of CH_3OH

Mass of CH_3OH = 0.250 mol CH_3OH × (32.04 g CH_3OH /1 mol CH_3OH) = 8.0 g CH_3OH

3 0

2 years ago