How many minutes are in 3.4 days

A chemical reaction is occurring in the flask below. Which energy diagram describes the energy changes that are taking place in

Gnoma [55]

C is the answer for this question

7 0

4 years ago

Read 2 more answers

Give reason why mendeleev's definition of transition elements is no longer acceptable

hjlf

Mendeleev's periodic table

Dmitri Mendeleev

Like many scientists working at the end of the 19th-century the Russian chemist Dmitri Mendeleev (1834-1907) was looking for ways to organise the known elements. Mendeleev published his first periodic table of the elements in 1869.

Features of Mendeleev's tables

Mendeleev arranged the elements in order of increasing relative atomic mass. When he did this he noted that the chemical properties of the elements and their compounds showed a periodic trend. He then arranged the elements by putting those with similar properties below each other into groups. To make his classification work Mendeleev made a few changes to his order:

he left gaps for yet to be discovered elements
he switched the order of a few elements to keep the groups consistent

5 0

3 years ago

Caffeine, a stimulant in coffee and tea, has a molar mass of 194.19 g/mol and a mass percentage composition of 49.48% C, 5.19% H

lozanna [386]

Answer : The molecular formula of a caffeine is, $C_8H_{10}N_4O_2$

Solution :

If percentage are given then we are taking total mass is 100 grams.

So, the mass of each element is equal to the percentage given.

Mass of C = 49.48 g

Mass of H = 5.19 g

Mass of N = 28.85 g

Mass of O = 16.48 g

Molar mass of C = 12 g/mole

Molar mass of H = 1 g/mole

Molar mass of N = 14 g/mole

Molar mass of O = 16 g/mole

Step 1 : convert given masses into moles.

Moles of C = $\frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{49.48g}{12g/mole}=4.12moles$

Moles of H = $\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{5.19g}{1g/mole}=5.19moles$

Moles of N = $\frac{\text{ given mass of N}}{\text{ molar mass of N}}= \frac{28.85g}{14g/mole}=2.06moles$

Moles of O = $\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{16.48g}{16g/mole}=1.03moles$

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C = $\frac{4.12}{1.03}=4$

For H = $\frac{5.19}{1.03}=5.03\approx 5$

For N = $\frac{2.06}{1.03}=2$

For O = $\frac{1.03}{1.03}=1$

The ratio of C : H : N : O = 4 : 5 : 2 : 1

The mole ratio of the element is represented by subscripts in empirical formula.

The Empirical formula = $C_4H_5N_2O_1=C_4H_5N_2O$

The empirical formula weight = 4(12) + 5(1) + 2(14) + 16 = 97 gram/eq

Now we have to calculate the molecular formula of the compound.

Formula used :

$n=\frac{\text{Molecular formula}}{\text{Empirical formula weight}}$

$n=\frac{194.19}{97}=2$

Molecular formula = $(C_4H_5N_2O)_n=(C_4H_5N_2O)_2=C_8H_{10}N_4O_2$

Therefore, the molecular of the caffeine is, $C_8H_{10}N_4O_2$

5 0

4 years ago

The table below lists the properties of a metallic element. Shiny, Silver colored, Forms +1 and +2 ions, compound with sulfur is

shtirl [24]

Answer:

The correct option is;

Group 12

Explanation:

A metallic element that is shiny and silver colored that can exist in the +1 and +2 ionic states and which forms a bright red compound with sulfur is mercury, Hg

The compound formed between mercury and silver is one of the earliest synthetic compound also known as vermilion and cinnabar. The bright red pigment of the HgS is used widely and is one of the most favorite pigment found in medieval European outstanding works of arts and in Chinese decorated wares made of lacquer as well as in mesoAmerica.

5 0

3 years ago

Read 2 more answers

Put the steps in the process of photosynthesis in order

shepuryov [24]

Step 1-Light Dependent

CO2 and H2O enter the leaf

Step 2- Light Dependent

Light hits the pigment in the membrane of a thylakoid, splitting the H2O into O2

Step 3- Light Dependent

The electrons move down to enzymes

Step 4-Light Dependent

Sunlight hits the second pigment molecule allowing the enzymes to convert ADP to ATP and NADP+ gets converted to NADPH

Step 5-Light independent

The ATP and NADPH is used by the calvin cycle as a power source for converting carbon dioxide from the atmosphere into simple sugar glucose.

Step 6-Light independent

The calvin cycle converts 3CO2 molecules from the atmosphere to glucose

calvin cycle

The second of two major stages in photosynthesis (following the light reactions), involving atmospheric CO2 fixation and reduction of the fixed carbon into carbohydrate.

4 0

4 years ago