Help Zone

FastFox1311

What is dimensional tolerance and what is the ± (+/-) symbol in technical drawings?

thankss

FastFox1311

Hello!

I have a lab tomorrow and I have to write a protocol for the dissolution that I have to do, where I have to use a 50 ml volumetric flask and I have to make a concentrated solution of 0.08 g / ml of NaCl. First, how do I calculate the mass of NaCl? Then, can you give me some tips for writing my protocol ??

Thank you !!!

FastFox1311

Hello,

Could you explain to me what a dissolution is? I am not sure I understand.

Thank you so much!

FastFox1311

Hi!

How do we know if we have a homogeneous or heterogeneous mixture? Also, in which of these 2 categories does a colloid fit?

Thanks already!

HumbleArmadillo3023

Hello,

I'm having a hard time figuring out what a cut and section are when it comes to technical drawings. Could you please explain it to me?

Thank you so much!

HumbleArmadillo3023

Hi!

In my science homework, I am asked to reproduce a drawing at 2:1 scale, but what does that mean?

Thanks :))

HumbleArmadillo3023

Hi,

How do I find the best possible orientation for a cut-through view?

HumbleArmadillo3023

Do you always have to put all views of an object in a multiple view projection? I find it long!

HumbleArmadillo3023

What is isometric projection used for and what is the difference with an oblique projection? Thanks for the help

SkillfulGrasshopper3789

Hi

I am having difficulty differentiating endothermic and exothermic reactions when using the enthalpy and not using it.

Can you help me? Thank you

TomateSupra7536

Hydrogen has a valence electron. True or false: it is part of the alkali metal group?

SkillfulGrasshopper3789

Hi!! Can someone explain to me the difference between temperature and heat? Thank you times a thousand !!

TomateSupra7536

In a periodic table, how do the electronegativity, atomic mass, ionization energy, and atomic radius of the elements vary?

TomateSupra7536

Hello,

I am having difficulty distinguishing the characteristics of metals, nonmetals and metalloids. Also, where can they be found in the periodic table?

Thank you so much!

TomateSupra7536

Does the way the periods are arranged in the periodic table mean anything? thank you

SkillfulGrasshopper3789

Hi!

I came across a difficult question:

Balance the following equation. Then, find the rate (in mol/s) of the reaction when 20 mL of HCl takes 30 seconds before reacting and form products. *The reaction takes place at constant temperature and pressure (25 ° C. and 101.3 kPa).

SXW7eVI3bCQf_iXiLZIXjl7H6Op784wtkwLySf-5RDbgjNq8944_hJcyTtTlTS2Cv4pTEYs7fYADlwb5eZV4Foy-blphn3niTMxdf5YzjKD8-ydVhwNzjOLU_mIBt-ElqFK8D7IU=s0

Ce contenu est protégé par le droit d'auteur. Toute reproduction à l'extérieur des forums Alloprof est interdite et pourra être considérée comme une violation du droit d'auteur.

TomateSupra7536

Hello! I'm not sure I understand why isotopes change the atomic mass of an atom ... Can you help me? Thank you very much in advance!

SkillfulGrasshopper3789

In one of my exercises, we must find out the quantity of product of a photosynthesis reaction such as this one:

CO2 + H2O → C6H12O6 + O2

The initial concentration of Carbon Dioxide is 62 mol / L, and the oxygen's concentration is 84 mol / L.

SkillfulGrasshopper3789

Can we add molecules and atoms to chemical equations when we balance them?

SkillfulGrasshopper3789

Hello,

I'm having trouble balancing chemical equations. Could you give me something, please?

Thank you so much!

SkillfulGrasshopper3789

Good evening,

I have a problem with the following question:

"In increasing order of concentration, order the following solutions:

Sol. A: 0.1 g / L of CaCO3 in water

Sol. B: 5% m / V solution of ethanol in water

Sol. C: solution of 3 mol of CO2 in 60 mol of air

Sol. D: solution of 560 ppm "

Thank you for your help

SkillfulGrasshopper3789

Hello!

I have an exercise in science which tells me that my concentration is 0.10 M. But what is the unit “M”?

Thanks already!

SkillfulGrasshopper3789

What is the difference between a mole and the Avogadro number?

SweetCrocodile1896

Can you help me with the following exercise:

“Name the different effects of forces:

We push on a concrete block
We pull on a rope
We twist a rag
We press on a wooden plank held by two blocks
We tear a piece of fabric “

SweetCrocodile1896

How do we distinguish between elastic deformation, plastic deformation and rupture?

HumbleArmadillo3023

Why is my answer (c) incorrect? Isn't there an accurate front view in an isometric projection?

Find the drawing

a)b)c) Neither; there is no front view in an isometric projection

Answer: a)

Ce contenu est protégé par le droit d'auteur. Toute reproduction à l'extérieur des forums Alloprof est interdite et pourra être considérée comme une violation du droit d'auteur.

Ce contenu est protégé par le droit d'auteur. Toute reproduction à l'extérieur des forums Alloprof est interdite et pourra être considérée comme une violation du droit d'auteur.

HumbleArmadillo3023

What are multiple view projections useful for? It seems to me that a frontal projection would do the job just as well?

HumbleArmadillo3023

What is the difference between the motion transfer and transformation mechanisms? I do not understand.

HumbleArmadillo3023

What is the difference between a motion transfer mechanism and a motion transformation mechanism? Can you give some examples? Thank you :)

HumbleArmadillo3023

How do you know which way a gear or wheel turns?

Help Zone

Science

Science

Filters

Help Zone

Science

Science

Discussion List